Hi again,

I am now seriously looking at getting a 2008 G35x sport!

From what I have read, some parts that are compatible on the regular g35 won't be compatible on the G35x such as exhaust or some suspension,
my biggest concern is exhaust as the first thing I will be doing it putting on a new cat-back.

any information about this would be great as well as your solutions to this problem if you ran into them!

 

Ensure that you get Sedan exhaust, not coupe. Also make sure it's for AWD, as I believe the Y-Pipe is different. Front suspension is different in several aspects between RWD and AWD due to the front axle, I can't say for sure about the rear suspension, but I believe it's the same. To the best of my knowledge the Cats/Test Pipes are the same between coupe and sedan, mid-pipe and mufflers are way different. Cleric can fill you in with better info, as he's about the closest you'll find to a walking factory service manual for these things.

 

I have never worked on an HR equipped X but like Joenavy said the big difference needs to be in the y-pipe to clear the transfer case. Call around to some reputable manufacturers and vendors and confirm their exhaust will fit. For example I know Fast Intentions makes an exhaust for your vehicle and they make some excellent quality stuff as well.

From a performance perspective with your HR motor the biggest gains will be, true dual cold air intake like the Stillen or Z1 Motorsports intake, high flow cats, Uprev tune.

Interestingly enough I've heard a few muffler deletes with the stock catalytic converters irl and it actually sounds really good on the HR sedans. Not raspy or wierd at all, if you want a louder more aggressive tone that would be an option to consider. I wouldn't go HFC with a muffler delete though, would probably be TOO loud.