how do i replace my stereo system

I would contact a local car audio shop, many will install for free with purchase of the unit.

There are some places that will custom make you kit that will fit to your specifics. I have a 99 Es 300 and had the hardest time getting a bracket and people wanted to charge extreme to do a custom kit for me...so I basically did one myself...with a protracter, ruler and enginuity, I carved the exact design of the opening of the block face unit on a 3/4 inch wood board...I went over the piece of wood with matte finish spray paint...let it dry...put a coat of schlack over that and then back again with matte finish spray paint....I get a lot of compliments on my system...I have a ALPINE head unit that mounts as if factory...my stereo system is nice...4 INFINITY 6 1/2 in the doors( 500 watt PUNCH amp on them) 4 LANZAR tweeters( 150 watts PUNCH amp on them) and 2 PUNCH HE2 12" subs(PUNCH 500 on them). Depending on what Lexus you have I have made a template of my design and will share with you if like...email me and i will send pictures of my work,,,I can be reache at sectorscorp@aol.com...my name is Larry, and i'm in the Dallas area..good luck to you in your endeavors..

Take a look at my photos. I found this on ebay, and painted everything to match.