Whenever I need helpful information I look on here. So hopefully someone could help me out. So recently I got custom short headers and exhaust put on a 01 maxima. It has one cat and so far no engine light. Only other mod on the car is a ram intake. When I'm driving and punch it, around 4000rpm it drops in rpm's to about 3600rpm then goes back up and keeps going. This happens in mostly 3rd and 4th gear. Any idea what this could be? Also anyone know how to cut the sound down a bit. It's super loud. I know adding another cat or resonator will help but is there anything else?

 

How long is your Ram air intake?

 

So you're sure that you're not hitting the brakes?

If you're serious about fixing this I'd suggest some serious information.

Video of said event.
Log of maf input.
Log of tps.
Log of rpm vs time with the aforementioned
Info about your car [01 maxima isnt enough]

And finally, moving this to the appropriate section, because honestly if you cant provide the aforementioned easily, this isnt a very advanced topic now is it??

My opinion? Change up the injector pulse timing, sounds like you have a nasty hole in 3rd.