Anything that improves airflow through a supercharged engine should result in a decrease of boost pressure. If the engine can digest the air with less effort, the build up of air (pressure) in the intake manifold will decrease. This doesn't mean the supercharger is pushing less air into the engine. Its compressor speed is defined by its drive ratio to the crankshaft. So lowering boost via improved engine airflow will only increase power: reduction in pumping losses and parasitic drag and improved thermal efficiency,

I've read just about every thread on this board about exhaust systems, but most just discuss the sound out of various offerings from different manufacturers, or that they allow for more horsepower over OEM. But given that the Nismo exhaust is more free-flowing than the base model, how much would be left on the table by staying with the Nismo exhaust for the A2A system, coupled with high-flow cats? I really don't want a loud exhaust, and am fine with what's already there. But will retaining the Nismo exhaust result in noticeably hotter operating temps, and/or higher boost pressure?

I've looked at the dyno sheets, and I'm not really convinced that the aftermarket exhausts do more in terms of horsepower than the Nismo system, which, by extension, would also suggest that they don't move any more air. Thoughts? Thanks!

If U want to stick with the Nismo Cat back that’s fine...to save u headaches in the long run ur gonna have to go with a LTH or Test Pipe...Exhaust temps will increase being boosted so u will eventually end up burning through ur Cats or HFCs...if u want something a little toned down then make sure u get resonated Test Pipes...they sound cleaner and are less raspy than straight test pipes

This. THey will eventually let go. Not as quick as HFC's but they will.

If you want the quietest test pipes on the market then look at the Motordyne ART pipes. THey sound exaclty like High flow cats.

Grf...I was hoping not to have to go this route...don't want to deal with the smell and possible drone. In another thread, it was recommended to have 100-cel blanks welded into pipes that positioned them further back -- would this work? Or, is this just an expensive way to delay the inevitable?

mil-spec (or some other very high end cat) located downstream appears to be a viable and reliable solution... though I don't know if anyone has been running it on this platform long enough to prove it out.

Tbatt runs 100 cell mil spec cats downstream, I'm not sure how long he's been running them though. I have a set on order and I'll be doing the same thing. Fast Intentions sells their lead pipes with 100 cell mil spec cats and Kevin said they work fine with forced induction.

For drone, here's what Tbatt did, I'll be doing the same mod also.

http://www.the370z.com/intake-exhaus...s-great-9.html

Thanks for the tips! I re-read TBatt's posts, and realized that he's got a Y-pipe. I think I've got an H-pipe on a Nismo? Haven't crawled underneath yet to check things out. I sent an e-mail to Fast Intentions to see what they say, and if they have perhaps a customized product. One thing I'm wondering is if a new wiring harness is needed for the O2 sensors if they are moved further back.

TBatt said the drone is reduced 50%, which has me wondering if that's still too much for me...

I'm running the standard FI TDX H pipe arrangement. The stock O2 sensor wiring works fine.

The new exhaust is much better than what I had but it is still kind of loud when accelerating. The main thing I was after was the constant drone at 70-80mph. It is now gone with the exception of load such as going up a hill. It's not bad but a little louder than I would like. Steady speed it is MUCH quieter!

Thanks for chiming in, TBatt.

Sorry for the questions, and I don't mean to sidetrack this thread. I just want to make sure I'm prepared ahead of time for all the parts, and don't discover any nasty (read: expensive) surprises after I'm committed. I also don't want to stray too far from my goal of having a civilized car to drive, that won't have my wife giving me the stink-eye over!

Related to the SC kit, do you guys think 4.08 gears would be a problem? If so, what would you guys recommend, 3.9, 3.6?

The SC wont mind at all! Your tires might.

Will i have driving issues and eventually move to longer gears? I am contemplating adding a LSD, but don't want do do double labor if I am going to swap out for longer gears later on.

It will drive pretty much the same as it does right now, just with a lot more power when you go heavier in the throttle. If you intend to rebuild the differential anyway, you may as well wait until you drive it with the SC and decide if you want to keep your gears or not.

I'm using the 4.08 with the A to A upgrade and its hard not to spin the wheels in first and second, but once you get going they're great and great on a track.