Catless downpipe for the Abarth. Would I end up hating life?

To answer the OP:  No.  An improved downpipe that still has a cat?  Sure.

I'm dealing with a rallyx car now that doesn't have the precat in the header.  What a pain in the ass.  

Also, health/environmental reasons.

z31maniac said:

Driven5 said:

z31maniac said:

Suprf1y said:

Without commenting on the moral or legal discussion, to suggest that there are no gains from removing a cat in a down pipe, or a pre-cat is incorrect. There have been significant differences on every turbo car I've done it to and in the latest non-turbo application it was dyno verified on a Chevy Colorado at 17hp.

This. Even modern Naturally aspirated cars pick up noticeable HP with cat removal and a tune. 

 

The Twins for example pickup around 15-20 whp with a cat delete and tune, only around 7-10hp with a tune, assuming pump gas. Not E85.

Were these controlled comparisons using otherwise identical systems, with the only difference being a high follow cat vs straight pipe? Same larger than stock piping, same muffler(s), same equivalent tune from same tuner?... Or is it vs smaller diameter stock, or some other such uncontrolled anecdote?  Sources?

Yes, there are comparisons using the stock header and just knocking out the cat. 

Sources? I have better things to do then go back and search the 86 forums for old threads to show you. You're more than welcome to do your own research, or perhaps you show me your sources that say it doesn't matter? 

Hell, ask some tuners if they have different tunes for catted and catless headers or catted vs catless downpipes on turbo cars, HINT: They do. Same on my 135i and many other cars, because their is a difference. 

I was going to ask if that was being followed by a stock cat-back, or larger aftermarket, but realized it doesn't really matter. I'm not talking about people who are penny wise but pound foolish... Just because knocking out the stock cat makes a difference, doesn't mean similar enough gains couldn't also be had with a cat too. It's not a question of whether or not catless can make gains, but rather whether any gains over a proper performance catted system are actually enough to justify the drawbacks of going catless. Honestly, I have yet to be provided with any evidence that it is.

That may be the question in another thread but not this one.

FWIW, in every application I've mentioned the vehicles still had cats. Just the pre-cat or cat in the downpipe was removed.