i have a 2005 impreza 2.5 RS and i want to give it more hp but i dont really know how to do it im only 17 so can afford things that cost alot so i need cheap ways

Asked by Aug 18, 2012 at 12:42 PM about the 2005 Subaru Impreza 2.5 RS

Question type: Car Customization

these ideas need to be cheap please

26 Answers

when i posted this i ment to say i cant afford things that cost alot


an intake and exhuast will be your cheapest


Intake and Exhaust are always the cheapest bets, but don't expect a really noticeable change in power until you can spend more money. For the exhaust there are a million cheap ways out there, just gotta pick one. For the intake the cheapest way I found is to order a Ebay intake, and replace the filter with a better name brand one.

2 people found this helpful.

Save your money, don't use it to try and squeeze cheap power out of a N/A Subaru motor. That motor specifically does not make power without plenty of work and financial support. http://forums.nasioc.com/forums/showthread.php?t=2362779

2 people found this helpful.

cheap, fast, reliable. pick 2....fast and reliable costs a lot of money but its the best route. a CAI wont give you jack. unless you do a full exhaust you wont get any power either. dont waste your money. save up and do it right once.

6 people found this helpful.

best way to do it is save your money and just keep it maintained... like everyone eles said if your gonna do the small things such as intake or exhuast, read into it, you might blow something out such as a cat or o2 sensor or relay... like i said to my buddy, the more fun you want out of your car, the more its gonna cost


ugh....I'm appalled that anyone said the words ebay intake in this thread. DO NOT under any circumstance get an ebay intake... you will likely lose power. now, first off an air intake (and a good one at that) will add a maximum of maybe 5hp by itself and will cost way too much to be justifiable. the stock air box has been engineered to get air from an outside source, and thus get cooler air than any "short ram" air intake which end in the engine bay and thus suck up hot air. I wont get into the details but cold air is much better. If you want to modify something on your air intake, get a good quality air filter such as a K&N. if you really want to do it, get an AEM intake and put ONLY the (usually chrome or colored) pipe on there but leave the stock air box in place, the stock piping is often less smooth than aftermarket intakes and this creates backflow that can be eliminated...it wont gain you much though. an exhaust is a much better setup. depending on where you live and what connections you have, it has to be kept legal (especially CA) for smog emissions. thus the catalytic converter (cat) needs to stay on the car. as far as a cat-back (after the cat) exhaust, there are tons of brands out there and they will not be too expensive. Now you have an NA 2.5rs (I'm going to guess) so the biggest diameter exhaust you will want to put on there is a 2.25in or at the VERY most a 2.5in. a bigger exhaust will not leave enough backflow, which is very important in an exhaust system (many people do not know this and think bigger is always better...wrong). I would go with what someone mentioned above and get a Borla exhaust. they are a good and reliable company, but then there are plenty out there, just dont get ebay crap...get a decent name brand. you will pay roughly $350-$500 for one. the next step is to open up the entire exhaust line but that will be more costly and will also potentially lead to legality problems. I believe (please check) that Borla makes CA legal headers. on a side note, if you want to keep the trademark Subaru bubbly sound, you will need unequal length headers. I would recommend running a high flow cat if you do headers and exhaust. the headers will run $350-$700 and the high flow cat is usually cheap at $200 or so. There is not much else that is "cheap" to place in a subaru. Everything gets expensive quick when customizing a car. now here is a thought though. If you want to go faster, why not work the suspension, brakes and chassis. If you start to modify your suspension and brakes, your car will handle quite a bit better giving you faster turning speeds and also slightly less shock sag in the rear on a hard take off (this also leaves you free to get an STI motor or build your motor later when you have more money). I would strongly suggest you go on Subaru forums and do a bit of research. You seem to know little about the overalls of modifying a car (thats not a bad thing...we all start that way) the best way to gain knowledge is to go read through build sites and forums. you will learn what works and what doesn't and interact with people who often have 5 to 10 to 20 years of experience on these cars... good luck with everything, hope this helps a bit.

17 people found this helpful.

for subaru's ive seen a lot of people start with a performance chip....not expensive and will give u noticable power when turned up all the way, and when ur not racing u can turn it down and get better fuel economy....if u get a chip then getting an intake can be beneficial because the chip can control air and fuel intake, so u can really get the most out of ur chip i would get an intake to go with it...also higher flow fuel injectors r fun to replace $200 - $300 for a set

1 people found this helpful.

^^ This, this is wrong. There is no "chip" that you can buy for these cars that is some miracle worker. You can do a full stand alone EMS, but those are huge amounts of money and time. The other option would be to build your own megasquirt EMS, which again, huge time commitment, and not very cheap. Then, you still have to find someone to tune the car at probably between $75-$125 per hour, all for a gain that will be minimal at best unless you do a complete motor build with head work and super high compression. Please reference the thread that I posted in my first response to give you an idea of how extensive this process is. @CJ, please do not answer a question with a response you are unsure of, it only spreads misinformation.

4 people found this helpful.

For reference http://www.diyautotune.com/catalog/megasquirt-iii-c-76.html http://forums.nasioc.com/forums/showthread.php?t=2362779 and that is NOT a street motor, it idles at 1400rpm.


for reference: http://www.performancechiptuning.com/Stage+1+Performance+Chip/8/ ....that one is made for the impreza, they have all three stages for the impreza.....and ryan just because u havent heard of it doesnt mean it doesnt exsist....look in any Classic Industries M=magazine or Jegs and there in there too....please dont tell everyone im lying and spreading misinformation ive built two cars from the frame up and studied automotive technology for 3 years....in that three years i was required to pick an "automotive science experiment" where we had to prove our conclusion with pages of facts....i chose "whats the quickest and cheapest way to add power without bolt ons"....its chips

3 people found this helpful.

:facepalm: I had no idea that you could just plug something in to your car and it made it more fasterz! Also, that electric procharger looks DOPE! If you brought these things up with anyone who is seriously involved in the automotive industry, they would laugh you out of the garage. These are some of the biggest and most well known gimmicks in the world, and the only reason people still buy them is because of people like you. But go ahead, prove me wrong, tell me exactly what parameters that they change, and how they affect both the horsepower and fuel economy while still being considered safe to afr levels and timing. You seem to be the authority on the subject, so teach me something then. Post your facts on google.docs and post the link here, I'll wait.


im talkin chips....i understand there "turbochargers" r not what u would call a turbocharger.....wheres Tom ive seen CarGuru's on here talking about them.....and im suggesting these things for people on a budget.... http://www.youtube.com/watch?v=2fbjxiC-yrs....listen around 1.10 he mentions performance chips


in detail on 1.45


I really didn't want to get into this pissing match but "chips" are shit. You need a full tune on the ecu to really do anything. Ryan is right here. Without seeing the afr and timing tables combined with the iats there's really no way to safely boost power in just adding a chip and getting anything worth while. You need to tune the ecu specifically.

1 people found this helpful.

ok fine, all i know is i cant pass my emissions on my trans am unless i set it to burn less fuel with my chip


ok what you really need to do is get yourself a cobb accessport... not a chip


chase is quite a bit more right than the rest of you, and Fyi, if you chip your ecu there is a large chance you will destroy your motor. a chip maxes out parameters that are NOT supposed to be maxed out (for example injectors). A reflash of the ECU with slightly more aggressive (but safe) parameters is doable but it is not too cheap and totally not worth it until the basics are done first. Again, go to Forums, you will get much, much better information.


@ Larry, they do not make an AP for his car. The methods I have already mentioned are the only way to safely tune his car @CJ, that means your shit is broken, and you should fix it instead of installing a bandaid. @Chase, thank you.Without seeing the parameters that the "magic chip" changes, it would make me VERY skeptical as to what it was actually doing.


....um no, it means with all my aftermarket....10:1 compression 350, new full exhaust, and performance quadrajet carb....it has trouble passing emissions as a lot of carbed cars do when u start adding power....engines been performance fine dyno tuned, it isnt gunna be burning fuel any more efficiently than now


Ryan and Chase, I completely agree. as for what the chip changes, it varies but its never good. it will usually have to do with either fuel delivery or ignition timing, not something to fuck with unless you know EXACTLY what you're doing and certainly not without SEEING the specific parameters as it gets re-tuned. @CJ...a trans am and a 2.5rs are not the same thing. I dont want to flame u but how much do you know about japanese cars and tuning because its very different from american. On another note, u chipped and then dyno tuned a carbed motor?? now i dont know as much bout american cars but where do you place a chip on a carbbed motor? depending on ur year the only reason I can think of off the top of my head for u to have an ECM on a carbed motor in a trans am is if you swapped from TPI to carbed in which case ur ECM is obsolete and the chip in it does all of nothing with the carbed setup.


well the main thing i noticed is that my choke would go on like 800 rpms sooner...but no under the passenger side dash panel there is a module under there with a chip that popped out and replaced with a Jet chip....and my car is an 84, they didnt start TPI until 85 for my car....if u can plug in a diagnostic reader, which u can on mine, then u can tune the information that gets sent to the distributor and anything else u have electronically controlled....


hu...interesting...learned something new. like I said, dont know tons bout the trans am. With a programmable chip on a carbed motor I actually dont disagree that it could help, but thats not the case on a 2.5rs. Ur also right on leaning out the fuel mixture to pass smog...its actually pretty common to do that. For the 2.5rs however (and most other japanese) I have not seen any chip which has been either safe or very helpful. If there is someone out there that can prove, through dyno numbers and showing EXACTLY what the chip does I'll gladly take a look but so far I have never seen anything substantial, just scammers trying to make money, and it always leads to problems with the motor in the end for the guy who bought it.


yeah, and i dont know if it will work well or not....someone asked a way to add some more power for cheap, i suggested a chip because everyone seems to suggest air or air filter or something....just trying to touch all the bases here....didnt think some people would get so worked up over it, just giving a suggestion

i have a outback 2.5 same engine i was in the same position as u, first word of advice is dont give up. now the best cheap upgrade for you would be a lightweight pulley, easy to install and you can feel the difference for sure and only for around 100$ you get a improved throttle response u can feel. next i would say is intake i currently have a weapon r secret intake lost a bit of low end torque but i would still recomend it draw back tho is it makes ur car sound like a ferrari some times but its not to loud next i would say start your exhaust to even out with the intake i started with headers and now i am planning to have a full custom exhaust done to it. next would be weight i took out the back seats in mine for a bit and i had quicker acceleration and cornering , feels like u can throw the car around its nice. but i put hem back in cuz of friends, so mi planning for carbon fiber hood. keep in mind that u wont get very good power but if your like me and just love ur car than definetly go for it.

Save your money for now. If you want to do mods that will have the most effect: sway bars. Seriously, the stock ones SUCK. I replaced mine in '12(I have an 05 2.5 rs wagon that I bought used with 60k) with whiteline adjustable bars. Of all my mods this has been the most important. good tires: get some good all-season tires. expect to pay about 100-150$/wheel. Currently running goodyear eagle sport all/season and have been for a while. maintain your car. Regular oil changes, transmission flush, spark plugs every 50k(MRI is 30k). don't screw with the engine, please. if you damage anything you are out quite a bit- and these motors are already at a much higher tune than most other 4-banger 2.5 liter motors. You may think you need horsepower, but you probably wouldn't be happy with 5-20 extra horse which is about what you can reasonably expect from an exhaust and intake(Which will run you upwards of 500$). Put the money instead in suspension and good tires, as well as taking very good care of the car. The sway bar mod can be done in an afternoon for less than 200$ and massively improves the car's ability to corner- I would start with that. More horsepower doesn't do anything if you can't use it.

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