ok , so i was thinking about getting a custom built straight pipe , but after reading forums about the rrm test pipe , i'll like to now , whats the difference between a regular and a high flow cat , is a high flow cat still legal , but at the same time , it will perform better for my car? what about the sound , would it change as well? because my problem is this , i live in nj , and the dealer shipped my lancer from cali , so i have 2 cat's instead of one , so i got a lot of restrictions. what would happend if i remove both cat and install a high flow instead? around how much would be the hp gain ? and would it still be legal ?....... sorry i know a lot of questions but i need answers asap , thanks

 

High flow cats are legal. The sound coming from the exhaust will be different from stock (i.e. louder), but it won't be as loud as running "straight pipes". As far as HP gains go, it depends on the rest of the exhaust, but something should gained if you stick to piping that's close to stock.

The difference between stock and high flow cats: stock cats are primarily designed to be cost efficient and very thorough at emissions scrubbing 1st with flow rate 2nd. High flow cats put flow characteristics first with emissions scrubbing second (while staying legal).

 

Thanks for the answer it really help i just hate when people answer without knowing ans say stupid s..t like (Get rid of that lancer) jajajaja

 

straight

 

High flow cat is "KINDA" legal. You'll be less likely to get in trouble, but you HAVE still tampered with the stock stuff (if you get caught).

HFC is going to be louder than stock but quieter than testpipe.

HP gain of HFC over stock is usually something like 1 hp on an NA car (if anything). Mostly, these are a good idea on a turbo car that wants SOME cat material for sound reduction and environmental concerns.

I vote do it - but be aware of the consequences if you get caught...

 

Check the cat manufacturer. The name brand stuff will usually have it's certification level. (CARB, CARB 2, etc)

And it's still illegal to have after market unless you have to have it replaced, and even then they want you to use an approved OEM cat.