cat-back useless without downpipe?

A 3" cat-back exhaust wont help me at all, until I get a 2.5" or 3" downpipe, using the "a chain is only as strong as its weakest link" theory.

Is my logic correct?

I don't know a good analogy to disprove the weakest link theory, but at any rate, a catback does help with a stock downpipe. That said, the downpipe is very important and I wouldn't install an exhaust in 2 parts unless I had a really low budget.

thanks.

just trying to make sense of what the exhaust guy had told me ,"catbacks are useless without downpipes for these turbo 4 bangers". which didnt make sense at all considering how well catback exhausts were doing for GReddy and Apexi's market...

The weakest link theory does apply to some extent, but more in the reverse direction. A 3" DP with a stock cat back would make MUCH less sense than a stock DP and 3" catback. In this order, the restrictions are additive for the most part. The other way around (upgraded DP) its more like the weakest link theory :)

The only issue I have with only doing the catback is that when you go to get a 3" DP, the catback wont bolt up without some modifications (the flange needs to be changed). I prefer to save up and do both.

Yes i agree i did it that way and i had to pretty much get the whole thing redone because it didnt line up right. get it all at once

just trying to make sense of what the exhaust guy had told me ,"catbacks are useless without downpipes for these turbo 4 bangers". which didnt make sense at all considering how well catback exhausts were doing for GReddy and Apexi's market...

First I think you should get a new exhaust guy.

If that were true then there wouldn't be a point of Dodge making the side-pipe for the SRT-4!

A tight, curvy pipe is a restriction, 'nuff said. I wouldn't suggest a 3" pipe unless you plan on 400+ hp and understand what it'll take to get that high in hp.

The other thing is that you can always upgrade later, suggesting high flow cat and larger downpipe. Then just purchase a collector and weld the whole thing up nice and tight and nobody would be the wiser.

And the reason Greddy and Apexi sell so much of that stuff is simply marketing. Most racers fabricate their pipes. They don't get them predone.

whatever the SoRryTurbo-4's are doing...

you are going to be upgrading it all pretty soon [or later] so i don't think it really matters too much as to the maximum performance you can get now on the things you got going.

and why not grab up an RRE DP? they are not too incredibly expensive and if you go with a custom fab exhaust system you can at least have a very descent exhaust system from the get go...