yeah there is nothing wrong with doing stacks on any truck. it won't effect the truck any and it will sound a lot better. I had intension of doing stacks on mine but lost interest. send me pictures after you do the stacks. here's my 89 toyota pickup.it look different now that I put 35 inch tires on it but here is a picture from before I did the big budd tires. it's custom camo.
i did just that... on my 88 yota 4x4 22re.... well i put a new muffler and cat (smallest i could find in front of the point where i turned it up through the bed... looks BAD ASS!!!! unfortunatly my head warped and started pissing fluids everywhere shortly after... it's currently in the drive waiting for money for repairs... but be SURE to have flexible hold downs on your pipe.. the vibrations will cause stiff ones to snap and it will fall onto your drive shaft... believe me...
The only problem that may arise is loss of low end power . Small cid engines need back presure to make power at low rpm . If you just run straight pipe it may not have enough back presure and could lose some power down low
thats why you do it after the cat. thats where you'll be able to maintain all the back pressure
Bottom line is it depends on how much of the back presure you free up . Without a dyno and some work trying different combinations you won't until you try it It may help it and it may hurt it It's a guess and mine is if you only have a cat and the rest straight pipe .It's going to make less low end power and more top end power.
Here is mine! Picked up bottom end and runs much better. 22RE 5spd
Here's another view, moved the stockairbox up into the scoop.
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