Are their any performance gains with the coupe midpipe + HKS installed? I mean more seat of the pants, not necessarily a couple HP on a dyno.

 

No, it has a larger resonator so it will make less noise.

 

not to thread jack but what does the 350Z Y-pipe do? and would it be a direct swap?

 

+1 on the above and what is "HR"???

 

Finally got the midpipe put on today, what a difference in sound, probably twice as loud, sounds very nice at start up. There is a slight drone around 1.5-2k but I'm loving it. As far as performance gains, I'm really not seeing anything different than before. Ill put some sound/video clips up tomorrow.

 

Nice setup you got going there. I got the same as yours, except I first installed the 05-06 sedan midpipe before the HKS. The middy upgrade brought a deep tone at idle, but once the HKS was on, the sound really opened up. The only way to notice a difference in performance is to do a dyno before and after the exhaust install, but I too have read up that these parts are designed strictly for sound improvement and nothing else.

 

go with the coupe midpipe

get a better y-pipe as well...hr is a good addition

here are few small clips of what it sounds like on my car

HKS, Coupe MP, HR y-pipe



here with Kinetix HFC and the above setup

 

The coupe midpipe is a better flowing pipe than any 03-06 sedan midpipes and additionally it offers lighter weight.

The HR (High Rev VQ35HR) is the newer style engine. They reformed the Y-pipe for better performance. It will flow better and minimize drone some.

Some HFC def. help the mix. I bet the HKS muffler will open up flow but only if you add other exhaust components. By changing only the muffler I doubt you'll see more than 2-3 HP.