so ive heard alot of mixed stuff about this, im currently @ stage1 looking to finally get that stage2 map downloaded, i but i need my DP i dont care about the smell i just want whats best for the car so ive heard that the catless DP's cause alot of Boost creep < which i dont even know what that means if someone could explain it to me >
So my question is what will work better for the car ? will the catless DP be fine ?
I currently have a Magnaflow catback with that cat still there.
so i have all the cats that came from factory still on the car.
Look at dumdum's post (#11). Basically he's saying without EM (to retune your WGDC, wastegate duty cycle) your 2.5L pushes air faster through a catless setup, causing spiking/creeping at higher engine loads. So the catless DP will be fine, just get EM (if you don't have any already). Any DP upgrade really should be accompanied by EM IMHO.
Okay so i can just get a catless downpipe from the private classifieds and be ready, its just so hard to stay on stage 1, the different it made was insane i just cant imagine how much faster it could be !
Just look at Cobbs Map notes, it tells you what to run with each staged setup. Catless is just cheaper than catted plus the boost issue, hat a at or not wont really matter power wise unless your pushing alot of HP through it.
alright here's another question. i've had a tsudo 3" catback and just got an HKS up and down pipe for a stock 04 WRX. If i were to go to stage 2 on the AP would this be bad because the HKS downpipe is not a bellmouth design...it is a 3" pipe though with no cats on either the up or down pipe.
It's a bad design, plus I change out of uppipe 1st as a safety precaution. I'm not sure how it would work with the hks DP, I'll wait for someone else to chime in. You should either way get rid of that DP and get yourself a bellmouth or divorced wastegate.
Edit: I just read in another thread you installed an UP, disregard that.
Thanks for all the help guys i ended up going with a Helix Catless DP with a Custom 3' TBE and i couldnt be happier, its ALOT louder than i expected it to be but i havent thrown and codes or anything from the turbo yet !