4" Cat? Oval cat?

[NSFW]

My conscience will allow me to ditch the UP cat, and one of the DP cats, but won't allow me to run fully catless.

Looking at dyno sheets I get the impression that cats actually do cost a fair amount of horsepower (like 10hp or more).

So I'm wondering if it would be feasible to get a catless DP and weld in an oversized cat, such as one intended for larger-diameter exhaust pipes, or maybe something with an oval-shaped cross-section.

 

Is there enough room under the car, near the end of the DP, to weld in a bigger-than normal cat? Stuff like...

 

http://www.car-sound.com/02product/universal/942.asp

http://www.car-sound.com/02product/universal/mirror.asp

http://www.car-sound.com/02product/universal/430.asp

 

Or is it just too tight in there?

[lucas569]

why spend so much $$$, time AND labor when you can get one of the many high flow catted dp 's???

[NSFW]

By "bigger than normal" I mean "bigger than what Cobb, Perrin, etc, are using."

[mickeyd2005]

I believe these are ceramic cats and don't flow as well as the metallic substrate cats that Cobb and others are using.

 

However, I believe these are more efficient in eliminating emissions and are actually legal for stock replacement after your car has exceeded the 5 year stock emissions period.

[hogmeat]

you'll pass any sniff test with a metallic cat - they are "small" but they clean it up enough. If it eases your conscience - I'm pumping the atmosphere full of hydrocarbons. Although, it's only at a rate of 3,000 miles a year