will a 3''o2 and a 3'' downpipe bolt on to my 2.5'' exhaust piping

[BOOSTED4LIFE90]

hey fellas! im about to purchase a 3'' o2 housing w/an atmospheric dump and a 3'' downpipe from RNR but i have a little bit of a problem.i have an Apexi N1 exhaust system w/ a 2.5'' exhaust piping and want to know if i buy the 3'' o2 housing w/the dump and the 3'' downpipe will it bolt right on? if not should i just buy the 2.5'' o2 housing w/the dump and the 2.5'' downpipe?all the info will be greatly appriciated fellas.thanks guys!

 

[69_luv]

Just for a little bit of info for you a Apexi N1 (3") downpipe is actually only 2.5 inches at the begining flange. And if I am correct, which someone here will correct me if I am wrong, the 3" o2 housing is actually 2.5" at the flange. So your problem would be at the flange from the downpipe to the catback system. I am supposing that you are not running a cat?
Go with the 2.5" downpipe, if you allready have the 2.5" catback. You can stay with the 3"o2 housing as I am pretty sure it bolts up to the 2.5" downpipe. I am running the 3" Apexi N1 GT downpipe and it is only 2.5" tell the flex section, then flares out to 3".

 

[djpast]

word of the wise: BOTTLENECKING IS BAD! i ran a 3" o2 housing, 3" downpipe and test pipe to a 2.5" HKS catback. i ran piss slower then i did with the stock downpipe and o2 housing. I switched to a custom 3" catback, and knocked .5 off my best 1/4 time

just remember this... then exhaust gases are hot, smaller piping is ok, but as they cool, they expand, so you are gonna have to try and force alot of air thru a smaller hole after it expands... this causing problems