[bike757]

i have a 99 civic with a d16y7 just got headers 2.25 will it work with stock exhuast or will i need a cat back.

 

[CapnToll]

You just have to make sure the flanges will match up...if not you'll have to get it custom fab'd. But, a larger than stock cat-back exhaust will help to make sure you don't create a bottle-neck situation. Just don't expect very much gain in power. Intake/Header/Exhaust on a d16y7 will net around 5-6whp....which you probably won't notice. What you will notice is a nice gain in throttle response, and the extra engine noise will make it seem a bit quicker.

I don't know which header you purchased, and where the bolt-holes on the downpipe might be to mate with your stock cat. There's a good chance they won't just bolt up easily because your stock cat diameter isn't close to 2.25''. I'm not too familiar with the d16y7 cat flange, so I don't know how universal it is.

 

[The Greatness]

actually the y7 motors cat is in front of the motor. most headers will bolt up to the factory exhaust. depends on the header though. if you install the header on a factory y7 you will not have a cat. the factory exhaust on a civic is tiny anyway. test fit the header onto your car and if it fits cool. if not you will have to buy a catback however i would recommend one anyway. when you buy a exhaust get one for a ex or si model so you can run a cat or test pipe. a dx exhaust wont give you that option so if you have to get emissions testing done your fuckd. if you get the ex si exhaust you can go catless with a testpipe and swap your testpipe for a factory cat when necessary. your car will sound much better with a cat but thats your choice.

the y7 motor has alot of potentail. a good header and exhaust will make alot of top end power compared to stock. not huge but noticable.