I have a test pipe that I havent installed yet because I want to find out if its okay to do so. It's 2.5", it has two holes for the o2 sensor. I drive an obdII integra ls. I was wondering if i need to plug up the other o2 sensor hole and would the computer be reading it as running too rich? Would I lose performance if the check light is on? Do I need the obdI to obdII connector? and is 2.5" be too big if i had dc 4-2-1 headers and 2 1/4 crush piping with stock muffler?

 

You can get a nice little thing called an "oxygen sensor simulator" that feeds a signal to the ECU to make it think there's still an o2 sensor hooked up.

As far as your choice of exhaust system and the fact that you're in California I would perhaps stay away from a test pipe. A high flow cat and a real catback exhaust with mandrel bent pipes will get you more gains than a header and test pipe bottled up by crush bent pipes and the stock muffler.

 

Hey thanks man, so you think its better to go with a good catback system and a high flow cat? and where can i get that o2 sensor simulator? whats the cost on that? One more question, if i was gonna go turbo in the future, i just need to get bigger piping to 3" and keep everything else right?

 

I had a test pipe made for my hatch and i didnt' like it at all, unless you have them make it like PERFECT FIT, which is very hard it'll have a big exhaust leak and you'll LOSE power, i got a high flow cat for $30 more than the test pipe but it was worth every cent, more power is going through.. so go with nice exhaust piping and high-flow cat, it'll be worth the money and time you put into putting it on.

 

i got my powercore race cat from landspeed racing. it's really no more than a baffled straight through test pipe(baffles around the outer edge but 100% hollow down the center). stainless steel, and already has 2 bungs for o2 placement. it comes with gaskets, hardware, and bolt to plug one of the bungs. fit like a glove. i paid $150, and to me it was worth every penny. throttle response was quicker and made a noticeable difference to me. car pulls nicer. but the exhaust did get louder.

 

that would be 1 of the points to a high-flow cat, louder. letting more exhaust though faster.

 

i got a test pipe from speedy muffler and they didnt charge me for it cuz the same day i got my straight pipe. they made it a perfect fit, 2 o2 sensors, and brackets attached. im happy wit it but i juss got a smog ticket... so cat. goes back on. u can go to some muffler shops... go in person dont call... and if they r cool they will make u 1 and hopefully be smart to measure things b4 cuttin. my friends have spent like $50 on them... its a lot cheaper than a high-flow cat. but u will have to do some work to save urself that extra $100 or so.

 

got my hi-flow for $70 shipped.