how much can horsepower gain can i really expect with a test pipe?? im running a 2.5" all the way except that my cat is stock.. Do you think that a test pipe will help with a significant gain??

 

i ont believe this is the place to ask the question, moreso to show the results..... might wanna try the 4th gen section for best reply, but just to answer your question, yes changing anything on your exhaust from its stock form gives good gains................ answer!

 

From what I have heard, unless your factory cat is in poor condition and clogged up, the factory cat is a high flow cat and the gains from replacing the stock cat with a testpipe is near insignificant.

 

more sound than anything.

 

as said above, unless your stock cat is clogged you wont find a huge difference. Whether or not it is an insignificant gain or not is a debate that has been ongoing and never ending on this forum, so do whatever you want and enjoy

Edit: make sure you get a resonated test pipe though, for the sake of yourself and everyone you might drive near

 

The increase in diameter of going to a 2.5" high flow cat from stock would give you some gains, but a test pipe won't be much more over that.

 

It's mostly a sound thing. I can tell you my exhaust with a high flow cat (it's tiny and may as well be a test pipe) is still relatively quiet with the right muffler but you can hear it backfire on deceleration a LOT more noticeably. Not in a bad way, really, just a sound most are not used to hearing because it's usually muffled.

 

from stock to a high flow, is respective gains, from a high flow cat to a test pipe is more sound than gain.... and the stock 5.5 cat is not a high flow cat....

 

I think 5.5's notice more from exhaust "upgrades" than previous Maximas in general, though. The 3.5 seems to respond a little better to those sorts of tweaks.

 

I have a warpspeed y-pipe and apexi ws exhaust. I had it installed without a cat for five months and it was loud and I also lost low end torque. I just installed a cat yesterday and now it is a lot quieter and the low end torque is back. A high flow cat is better for performance though.

 

i agree... oh and i couldnt help to notice your avatar........ Playstation???

 

well, if you installed a Y-pipe and a catback with no catalytic convertor, then your exhaust is pointless as you was just driving around open headers... so how you figure the high flow cat is better, cause to be honest dudes are running cutouts and is getting more in the ET's soooooooooooo yea