Well I have already ordered my catback, and my next mod will be a downpipe along with ap. my question is, is it worth it to get the catted downpipe? is there that much power lost from a catted to a catless? Yes emissions plays a factor there, but is it really that big of a deal? Any insight to this would be greatly appreciated.

If I can get the same power gains and still keep the cat, which can be helpful with emissions, id rather go that route.

 

I am thinking of going stage 2 cobb, and have a similar question. One issue I have come across with no cat is there may be problems with turbocreep, and overboost. I would like to here from people experienced with this issue also.

 

BUMP..i would like to know also.. thanks!

 

I have an '02 with non-catted TBE and I went about 2 months with no problems but lately I've been overboosting. I will be getting an AP real soon and that should help. I think that having a DP with a bellmouth is part of the problem (not 100% sure though).

As far as the difference in power gains from a catted or non-catted....I don't think it's a differnce large enough to get the non-catted if you have smog checks. I don't have to worry about emissions so I got the non-catted.

 

probably about 5 or less HP lost. which should not be big deal in power especially with emission. on a 06 wrx or STi..running a cat and ap would help not to get a boost creep/boost spike. When you get the time and money get a protune, NO TWO CAR ARE THE SAME. protune your vehicle for full potential of your mods AND safely run ur car to the max with those mods, very worth it.

im currently running stage 2. love it! NO BOOST CREEP.

Current mods ARE:
invidia catted divorce wastegate.
HKS hi-power catback
AP (stage 2)
soon to have protune.

 

no sense getting a catted version, messing with any of the factory cats is illegal in CA. mind as well save some cash and get the non-catted if your gona be breaking the law anyway

 

true, but if you go for an inspection, and all they do is just look under the car, and see the cat there, that helps a lot more. places in cali dont have awd dyno's to check our cars, so they just do the visual inspection.

lburrnna, you said you have the invidia with the divorced wastegate. is that also a big deal? that was one of the dp's that i was looking at, but i wasnt quite sure how beneficial the divorced waste gate was.

 

i would get catted...for one you can pass emissions...and 2 you won't stink like exhaust everyday..i was catless in my last car and never again! mild headaches and the smell was just too much...i was actually behind a catless wrx 2 weeks ago and had to put my windows up because his car smelled like ****

this was taken from PDE

What's the difference in flow between Catted and Cat-less PDE downpipes?
As measured on a Superflow 1020 Flowbench, with ambient air temperature correction enabled:
Stock Subaru WRX Downpipe 260.4 CFM @ 28" H2O

PDE-1005 WRX / STi Downpipe (with Cat) 414.1 CFM @ 28" H2O (59% increase over stock)

PDE-1002 WRX / STi Downpipe (Cat-less) 475.8 CFM @ 28" H2O (82% increase over stock)

 

I got the Invidia V3 Catless downpipe on my 06 wrx. I have the cobb ap stage 2 upgrade also. No problems yet with boost creep or spike. I have had it on about 1 month. The only problem is the smell, but you get used to it. It backfires a lot louder without the cat also.

 

I would go with a catless Cobb downpipe.
I have heard of people passing CA emissions testing with a catted
version downpipe.

 

(I'd think that would be a reason for buying the catted DP).
So there has been no issues of boost creep w/the non-cat DP. I went w/the Cobb catted DP TBE because I heard of issues going w/a catless DP & boost creep. Was I wrong? My 06 STI is a daily driver & I didn't want tuning isuues w/boost creep & subsequently went w/the catted Cobb DP because of the info I got. I'm assuming the difference is minimal & I'm not really too concerned as far as power deficit (not to mention getting ahold of Cobb exhaust has been difficult).

 

for you people with catless downpipes, does it ever smell inside your car??? with my windows up, i can smell it sometimes, and its a strong smell. i can usually smell it in city driving when i am stopping and going. i need to put down my windows and turn on the AC cuz i cant handle the fumes.

 

haha ya i just put a catless downpipe and the whole deal exhuast, and and for the first week i was like what the hell is that then i relized it it was from the dp, but its not that bad like the only time i smell it, is when i park in the garage and get out i drive around with my window down all the time, and feel bad *** cause of the sound.