hey i have a 04 6mt coupe im looking to get some high flow cats on my G and i just saw the new stillen ones and i was wondering if anyone knows anything about them or how they compare to crawford or kinetix ?

 

The longevity problem with the so called high flow cats is a future consideration, since the matrix comb is more open and has a thinner coating of actual catalyst. They usually don't last more thantwice warranty ~~ 24,000 miles vs >100,000 miles for oem.

It is illegal to change working oem cats for inferior aftermarkets but hard to get caught in this felony violation of Clean Air Act.

 

^True. And the "High-Flow" cats really don't do much for overall system flow as the cats are not the bottleneck anyway. The stock manifolds are far more restrictive. Unless you are going to install headers, not really worth the time and money and rasp and legal risk.

 

If you are going illegal throw some test pipes on until you have the inspection.
No one makes a legal aftermarket hi flow cat so why bother.....just don't get
ticketed/nailed/caught with test pipes!

 

From what I understand, on a NA setup, TP's will only give u a few more ponies that a quality mettalic HFC. Along, w/ that slight boost of power u will likely experience unburnt fuel fumes sneaking into the cabin, much more rasp, as well as causing more pollution to the environment (which some may or may not care about).

 

Testpipes typically get about 2-3 more HP and 1-2 more TQ than a good HFC. 300 cell metallics will flow about the same - less variance versus the 400 cell Ceramic cores.

For longevity - you'd want the metallics - if your staying NA - not modding much, etc...go ceramic - a bit smoother sound.

Rick

 

I say go with the metalics, but that is just me.

-Sean