do a custom exhaust.if it is done correctly it will have better gains than the TRD
/tanabe axle back exhausts.
you said that you have a shop that does exhausts right,ask them if they mandrel bend the piping.
if yes,you can get a wicked ass exhaust done for little or nothing but material.
what you need.:
1) 2.5 inch internal stainless steel pipe(check ebay)
2) 2.5 inch flow through cannister(stainless steel)(check ebay,get something with a 4.5 inch tip out,like the dragger or the obx pan that looks like the gready muffler.i checked and compared them almost no difference in sound and performance.
3)optional buy a 2.5 bullet style muffler (check summitt racing get the 12" one)
this is in case you like your sound more deep but it will drop the output slightly(depend on where upstreem/downstreem you put it)
you are to let the guys at the shop cut your exhaust off behind the back o2 sensor,the 2.5 inch pipe will be opened up and the pipe thats left(the piece thats hanging after its cut)goes into the pipe(not butt joined,it cant go over cause 2.5 inch is too big)
you are to make sure that the edge of the pipe is grinded down smooth inside and out side,and should fit snug.
have the pipe mandrel bent all the way back to the axle,making the least and shortest possible bends.(it will curve around the suspension in the middle(other routing is possible but i dont know if you are dropped or planning to)the 2.5 inch canister will be placed at the back,again the pipe comming from the front goes into the canister(not butt joined,and the inner edge of the pipe shound be ginded down or sanded flat,the canister will have to be opened just enough so the pipe gooes into it and fit tight.
you should now have a 2.5 inch mandrel bent pipe all the way to the back with a 2.5 inch fow through cannister at the back.at this point have the guys start adding the hangers(factory locations are best)hang the system,at this point the optional bullet style flow through muffler can be put in if the car is too loud.you can actually start the car and get an idea of how loud it is even though the system has not been welded(it should fit tight enough to start.)if its too loud,put in the bullet muffler,the same thing goes,pipe into the muffler and out of the muffler into the pipe.(everything upstreem goes into what ever downstreem,not butt joinrd or go out side of)
muffler placement:(the bullet style)
it can be placed from just after the cat or as far back as just before the cannister.there is a difference.
closer to the cat(upstreem) would clamp down more on pops/resonance/turbulence but hinder performance slightly.more downstreem will have less impact on performance but less clamping down on
pops/resonance/turbulence.(a compromise can be met somewhere your choice)
welds:tig or mig weld.
the pipe should have overlap within the pipe you would weld all areas to be welded after the muffler is hanged and marked to make sure its not hitting the bumper,suspension,body etc. as long as you make sure that the pipe is grinded down flat where its going into the following pipe and that there are no edges inside,flow will be good and less buzzing noises.
additionally you can wrap the entire exhaust and header all the way back until just before you can see it(if your like that "can you see my stainless steel kind of person")it will help to increase the flow,thus hp.
note:remember stainless steel dont have to be as thick as mild steel so it is better to do a custom set up(weight savings)
and dont fuckk the car up by rushing,make sure everything fits perfect before you start welding off,if you make a mistake it will not be clean,and chances are the welds will leave material on the inside if you have to reweld it more than once.