Has there been a thread about this? if so can you post the link? Ive been searching but i didnt see anything. Basically im trying to figure out how the stock cat compares to the after market high flow cat. Is it that restrictive that it needs to be replaced? I am in the market for HFC. any suggestions or experience you would like to share?

 

First mod I did to my exhaust components is the removal of stock cat to HKS metal catalyzer. It made quite a noticeable difference immediately: quicker spool, improved response and extra power from mid range onwards.
Keep in mind that metal catalyzer are better than ceramic contruction, and find one that has less cell density as it provides better airflow.

 

bottom line, the stock cat is a lot more restrictive than any hi-flo cat. i am running the ur metal substrate hfc, pretty good gains without the smell

 

The stock cat is leaps and bounds better than aftermarket catalysts.

we're talking about it's catalytic function, right?

 

take it out, plant a tree

 

Test Pipe > HFC > Stock Cat

It's up to you & your state laws you have to deal with.

 

stock cat is more restrictive that aftermarket but by how much? it appears to be huge in diameter so it probably doesnt flow that bad.

i would say that the muffler piece is a bigger restriction than the stock cat

 

High flow cat is my choice

 

Test pipes are not even an option i looked into. I know that the test pipe will give me the most gain in HP, but I would like to stay "Legal" and dont want the stinky smell. So its down to HFC or keep it stock.

I have replaced my mid pipe and muffler...DP is coming as well...So with all that replaced, i guess i just wanted to know if the stock will still be that restrictive? But it seems like its best to just replace the stock and go wtih HFC

 

You can get any TP with a HFC. Just which ever one you like and can afford, they all do the same thing.

 

monchy, does your high flow cat pass inspection in NJ?

 

i dont mean to be nit picking but there is no such thing as a testpipe with a hfc.

test pipe is just that, pipe with no cat

 

100 cell race cat (search it on here). More power than a HFC, doesn't smell like a test pipe.

 

^ something to look into.

 

yeah i'd like to know if using perrin's hfc downpipe would pass nj's inspection.

can anyone also tell me how much louder a stock exhaust gets after putting in a downpipe?