[JAY07]

Ok i've been doing some searching and cant find my answer. For the 07 sti, what would be the diff. in getting a dp w/a cat or w/out a cat. I have the AP and will soon be getting a dp, when i find this answer. I've read everywhere that catless can mess ur engine. If it is protuned will it be ok to go catless? Any recom. on headers and exhuast to go with this set up. I dont want a loud exhuast that you can hear inside the car while traveling at low rpm's. THanks for the responses!!

[Phil 05]

U will need an eng mgt program of some kind w a dp, whether catless or catted. I am not aware of any catastrophic eng. damage due to a catless dp. I have a catless dp myself and my tuner did not think there would be any engine probs because of the no cat dp. There is one further down the line on your exhaust midpipe. How much of a diff in hp w a catless dp, if any, compared to a catted dp, i am not sure. Maybe another member can answer that question. If you're concerned about the whole issue, just order a catted dp, all the mfgr's make them both ways. There is obviously less restriction w a catless dp and therefore, better flow. You could call the mfg. of a dp, such as Invidia, and ask their tech dept. if they know what the diff in hp would be.

[Spoolin415]

Originally Posted by JAY07

Ok i've been doing some searching and cant find my answer. For the 07 sti, what would be the diff. in getting a dp w/a cat or w/out a cat. I have the AP and will soon be getting a dp, when i find this answer. I've read everywhere that catless can mess ur engine. If it is protuned will it be ok to go catless? Any recom. on headers and exhuast to go with this set up. I dont want a loud exhuast that you can hear inside the car while traveling at low rpm's. THanks for the responses!!

About 5whp. There are overboosting problems on the 07 while running catless. You also have the associated smell, extra sound and possible ticket while going catless. You should really get a protune before running a catless dp on an 07.

That said, I'm catless and I love it. APS 3" FTMFW. Headers depends, you want EL or unequal length. Equal length will take away the classic Subie sound, but give you more top end. You'll gain more mid with unequal aftermarket and keep the Subie rumble. Either way, you'll also need a protune for headers.

[JAY07]

I love that subie sound, so I'll prolly go with the UEL. Any thoughts on the Maddad header or the GT spec. Would there be a better one in the same price range? Thanks!!

[funSTi]

I went from catted to catless, it may be a little louder, but the smell is a lot worse but I tend to like it. If you want to go the safe route go catted, if you want that little extra then go catless!!!

[07 Flt4bxr]

i went catless at 1k miles. u must get protuned if ur catless for security. i love it and glad i went catless on my 07.
if u dont want it to be loud than go catted and headers will only make it louder as well... i love my boxer rumble and wen i 1st got my tbe i was scared i was gonna hate it cuz it was too loud.... now im used to it and want it louder

[Jaylyons1]

the only bad out of a catless dp is a gas smell. If the car is tuned correctly you will only get it upon startup, or maybe a random whiff every now and again. But you do can tune about 5 extra HP out of a catless.

[07 Flt4bxr]

Originally Posted by Jaylyons1

the only bad out of a catless dp is a gas smell. If the car is tuned correctly you will only get it upon startup, or maybe a random whiff every now and again. But you do can tune about 5 extra HP out of a catless.

ya i noticed the smell wen i 1st wen catless but after a few days the smell wasnt even strong at all.
and the higher flow is deff worht it
and at WOT u can deff tell someone is cattless with the pop that u get between shifts

[Kzuk21]

Just thought I would throw this out there, I have an 05, and was planning on going catless. Would I be alright with just running EM or do I need to get a protune on my 05??