I just had my catback put on finally and my car seems really really slow. But I have it 3" all the way back until the muffler which is only 2.5". I already ordered a new 3" muffler. I'm just wondering what would clog up my system more. A catalytic converter or a crappy muffler? Cause I really don't wanna change the cat since its all nice and welded up.

 

3''all the way back? yet a 2.5'' inlet to the muffler? That right there is your restriction, an exhaust system is only as good as it's weakest point..

 

if the cat is original it is prolly time for replacing or removing

 

Looks like it's time to gut the cat....
That's one good thing about living in Indiana, no emissions testings so we don't have to have cats...
It's either that, or you have a really crappy muffler.

 

i would think muffler also..
what cat are you running? could of clogged up for some reason.

 

Its a brand new cat. But I have a 3" muffler on the way. So once that comes in I'll find out if its my problem or not.

 

If your using the flowtech y-pipe the collector would be another if not the biggest resriction.

 

It is more important to have the larger, free-flowing system close to the engine than it is to have it back at the muffler. That is because exhaust is not a constant flow but a series of pulses. The 3" intermediate pipe will act as a plenum to "collect" the pulses so they can still flow out of the 2.5" muffler without a significant effect on power.

A cat will cause about a 5 HP or less loss. You'll lose that much power when the temperature goes from 60 degrees to 85 degrees. The cat does a good job of cleaning up the exhaust, so be a responsible citizen and keep it in there.

As to what I did myself: I used a high-flow 3" cat, like you. My cat-back is the Pace Setter system from JC Whitney. The I-pipe and tailpipes were fine, but the muffler inlet was 2.5", expanded to fit the 3" I-pipe. I quick ordered a 3" inlet Flow before installing the system.