wondering what the hp gains are from stock downpipe with stock cat versus aftermarket downpipe with high flow cat. 5hp? 10 hp?

need smog and i think i am going to just swap back to stock.

thanks.

 

not that much gains really without further mods. yeah something like 5-10hp. The thing with making power with our cars is that components only become restrictive at certain power levels.

Great example is air intakes and intake manifolds. On Subarus these don't really matter until you get a lot of horsepower. And on the intake manifold, it seems not to matter much until you get like 600hp.

Cams and headwork too. On stock turbo and pump gas boost levels this makes barely any difference. Much more when the airflow is greater via more boost or bigger turbo.

 

^ I thought it was like 400 or 450 whp?


Anyways to the OP if you are running a hi-flo DP you should pass smog.

 

You can feel the power increase slightly in an sti, but fact of the matter is you just don't really change the parts on the car and not get a tune.

 

just with turboback w/ high flow cat and cobb accessport 2, i gained ~50hp.

220 stock on dyno, then to 270.

i'm not sure what just the downpipe will have.

 

Dude the guy has an N/A impreza, not an STI.

 

it's actually for the 91 legacy ss.

 

won't pass visual unless you know someone

and i don't know anyone.

 

If it has a cat why wouldn't it pass?

 

because this is California and we have laws

 

fixed.
________
Marijuana Vaporizers

 

qtf

 

If you're going to break the smog **** law you may as well go all out and get a catless setup! Think about it...its a 91 Legacy...pretty sure the popo isn't thinking you're out there street racing with grandma's grocery getter

 

indeed....

doesnt matter if it has a cat thats more efficent or not...if it's aftermarket (ie made for performance and not an OEM replacement) it's illegal...doesn't even matter if it's catless and still is more efficient than stock....still illegal. F' CA in the **** for cars

 

I see