Newbie here...i was wondering what modifications would give a good increase in hp for an 04 wrx without taking away the cats. Any info or suggestions would be greatly appreciated. Thanks.

 

Easiest ,and maybe cheapest, hp for $$$? is ecu flash. I mean no mechanical skill required just an apptitude for directions and a lil bending over to get the flasher plugged in.

I suppose beyond that your a lil limited since exhuast is key for adding potential on this motor. You could keep a cat with a catt'ed downpipe, more expensive and doesn't pass smog where i live but an option for others.

I don't know the benifits of raising boost levels on a stock exhuast system so i wont even try but i'm sure someone else could break it down for you.

 

gotta second that. Go with the reflash. Personally I prefer the AccessPort, but there are lots of options for that.

Roadspike is right though, there's not a whole lot of power to be made from a WRX engine or any turbo engine for that matter w/o freeing up cats.

 

you could replace your turbo and intercooler and keep the cats...you'd still need a tune though

 

Thanks for the info guys...i had the ecu flash in mind and i wanted to see from everyones perspective what they would do if they were to keep their cats just to be smog legal. I am mainly going for looks rather than speed..but if i had the chance to upgrade and work my way around the cats then i would. I am also planning to keep the stock turbo. So yeah...other than an exhaust upgrade and the ecu flash, what would you guys do? headers maybe? pulleys? keep the info coming...thanks!

 

Here's a few opinions

Headers? testing showed not alot of bang for your buck as far as headers go but an up pipe (takes out the precat) would get a mildly better spool up time, sooner that turbo kicks in the better. (not alot of gains here far as i'm concerned)

Pulleys? I don't like them as they cost alot but it seems plenty of other people love them. https://www.i-club.com/forums/engine-power-ej20t-pre-2006-wrx-jdm-60/perrin-crank-pulley-installed-results-71479/

You could lighten your flywheel going on the basis that if you can't have a more powerfull engine you can lighten the drivetrain and make it spin up faster. In fact lighten everything you can

You should get an opinion on cams becuase i don't know anything about them

Get an opinion on a race tune , race fuel or not, since they work well on modded cars but i'm not entirely sure what you'd gain on a nearly stock system.

 

you can get a Helix catted downpipe which will pass CA smog. If you can get a letter from an auto shop stating that your original equipment no longer worked and needed to be replaced, you should still pass the sniff test and inspction...and you can replace all 3 cats with this one and still be ok...and if it passes CA smog it should pass everywhere else.

 

or you can get a JDM STi uppipe (they are generally pretty cheap) and they are catless.

You can't even tell that its not the stock part..they look exactly the same.

 

Where could I get one of these?

 

why bother? The USDM STi uppipe works just as well...it fits the WRX. Aftermarket pipe gives you about 4-5 HP more though.