I have an authentic hks paired with art pipes and I'm getting bad rasp between 2k-3k rpms, I heard that the x pipe will reduce drone/rasp. My question: is the hks h pipe 2.5 inches or 2.25? Thanks

authentic hks is 2.25

My authentic cat back dual HKS exhaust is 2.5" in diameter and why I replaced the crossover with a 2.5" X-Pipe from Magnflow. When installed the x-pipe (#10781) needed to be stretched so it would slip on before being welded...Gary

Unless they had QC issues, you got one from a batch that was made with slightly larger piping.

Officially they were advertised as 60MM (around 2.36in). Here they are known to be 2.25. The reps are 2.5 (I know that you have a authentic one though, Gary, just stating the diameters found online).

Like Gary said though, a 2.5 xpipe might be best though that you in case yours is larger you can weld, or you can slip over it and weld it.

To double check,
http://www.hksparts.com/hks_hi_power...1013467143.php
states it ranges from 55mm to 95mm

https://g35driver.com/forums/1771584-post1.html
CZP Info: 60mm

Let us know what you find once you add the Xpipe and we can put an end to this grey area!

Hey guys, just giving an update on the magnaflow resonated x pipe ( Part # 11385). Had the H pipe and resonators cut off and had the resonated x pipe installed in place of it. It turns out the 2.25 piping was correct for my authentic HKS exhaust. Here is a pic of the H pipe, notice I don't have the protrusion that accordfreak had in his H pipe, however correct me if im wrong, the holes should be bigger. They were only a 1/2 an inch and were not centered.



Here is a pic of the right side.




Here is a pic of how the maganflow looks on the bottom of the car.


and another



Before install: car at WOT around 2k and 3k rpms would rasp like a cheap honda, also would drone at higher speeds.


After install: Car is noticeably quieter at start up. At WOT I hear no rasp/drone whatsoever. The rasp is completely gone throughout the RPM range, it's a little bit quieter but has a deep sound to it. The exhaust now sounds like a mixture of the stock vq and the HKS. The total cost of the part and install was only $180, and was well worth it. Thank you to everyone who helped me.


My current setup: Art pipes, authentic hks, MD 5/16 spacer, popcharger and ztube

So whatd u do to reduce drone lol. My stillen exhaust has it now with art pipes and it sounds like s&@t after 3k rpms. Sounds awesome below that....

The x pipe eliminate all drone whatsoever, at least for me

does it reduce performance though

Honestly, it feels like I gained some low end tq, but I don't know for sure, just a butt dyno. I don't feel a loss though.

I am getting some terrible rasping, droning, vibrating around 2-3k and my set up consists of...

Megan racing test pipes --> Magnaflow midpipe/x-pipe --> knockoff HKS rear mufflers

at first i thought it was the flex pipes because they look kind of beat but It's noisy revving into that area ... decelerating and possibly acceleration but it is getting so annoying ! just want a clean sound all around

Hmm I wonder why
Def not because a shitty Megan product or a knockoff exhaust.
I'll keep researching other possible options for you

If the Megans have an empty looking container that look like they should have cats, then that would create a lot of rasp.

Your going to need to determine WHERE the rasp is coming from. Front middle or back end. The resonated X pipe can reduce rasp but if the mufflers are creating it, there's nothing the x pipe can do about that

middle

Then I suspect it's the chambered test pipes creating too much rasp for the X pipe to handle. If in fact the rasp is coming from the middle

Have you tried checking for any loose heat shields ?