if anyone is trying to get the o2 from ebay, i've got it, and its crap. it's not even ported well. i'm planning on putting my stock o2 in. if you're planning on getting an 02 housing, get the invidia one. its the biggest one out there. 2.9" compared to other 2.7" ones. DO NOT get the ebay o2. waste of money, no difference. maybe even lose power.

 

Well I guess you didnt get the real Ebay 02. The Ebay 02 everyone runs is ported very nicely, welds are perfect and its 10x better than the stock 02. Buschur did testing on it and it made more power than the Invidia AND Works which are both bigger in diameter. You dont need a 2.9-3.0" 02. 2.5" wil suffice for up to 500whp+

 

buschur says otherwise.

 

I have the 10.5 hotside and ebay o2, also had a rmr licp installed at the same time. Car runs much smoother especially with the a/c on(IMHO)! quicker spool in the gear and a tad more top end in fourth and fifth. Either way to me it was a noticeable difference. You may also notice a different noise when the turbo spools, I think it sounds pretty cool. Nothing wrong with my ebay o2. Overall its a great upgrade. I am happy with it.

 

would 10.5 and o2 necessitate a re-tune?

 

Some will say no as it is on the exhaust side of the motor, but I personally would get retuned when messing directly with the turbo and reducing the back pressure that much with the O2 housing. As far as do you really HAVE to get one like with an intake or cams or something? I dont believe so.

 

Yes you do 100%.