2.5 down pipes

[97cutlas$upreme]

ok how effective would it be if i went up to 2.5 on my down pipe? and would i do that to the one that wraps around the block coming from the front and underneath my intake? or is that possible? also what results have any of you got from going with a high flow cat and whats a good one to go with?

[SappySE107]

The crossover isn't the downpipe, Going larger there then smaller at the rear manifold will hurt. You don't want your exhaust gases to expand and then go through a smaller opening. The downpipe being 2.5" is fine if your system is 2.5" as well. I haven't done a larger downpipe on any of my setups to tell you what it will accomplish.

[gpse3400]

They work better than just tossing on a cat back. If you cant afford all out headers this is the next best thing. INstall this before putting on a larger cat back system, otherwise you'll just make extra noise. Pushrod engine typically came with a small 2inch. Later they welded an outside pipe around the 2inch down pipe to aid in catalyst light off. Your car being a '97 will have this double walled pipe setup. Chop it off (or find spare at the salvage yard)and go to you muffler shap and have them remake a pipe in 2.5 inches and re weld to your existing flange. You'll notice an all arount better feel of the engine. Depending on shops they might charge the most $60 to fab up the pipe and weld it to the flange

[MMGT1]

Had full intake(CAI) and cat back exhaust(including high flow cat and no res) before engine work. Ran consistant 15.2 all day. Had custom downpipe installed at Pipes Peformance in Toronto and saw 15.0 in the quarter. So the downpipe gained me 2 tenths and a couple mph at the trap.

So, yea it's worth it!

[97cutlas$upreme]

Had full intake(CAI) and cat back exhaust(including high flow cat and no res) before engine work. Ran consistant 15.2 all day. Had custom downpipe installed at Pipes Peformance in Toronto and saw 15.0 in the quarter. So the downpipe gained me 2 tenths and a couple mph at the trap.

So, yea it's worth it!

what kinda of cat are you using any in specific?

[MMGT1]

Nothing specific. The cat only cost me a hundred brand new so nothing fancy....

[97cutlas$upreme]

cool i guess thats gonna be the next project after my suspensions done thankx