I've noticed thru all the research and reading on here that most of the owners that have upgraded their exhaust have gone with FI, invidia, MXP, maybe meisterschaft, ARK, and surely a few more other reputable companies. To each his own reason for choosing. Anyways, I've seen or heard these setups matched with either HFC's or test pipes(ARKs were kinda raspy) and the results are quite pleasing and these results are discussed here BUT, for the owners of an HKS exhaust, it seems like no one has given any input whatsoever.
As an HKS owner, i figured i'd take a stab at it and see what i could come up with. I've heard a 370 with tp and hks matched up but there seems to be an incredible buzz associated with the setup. I just recently added tps to mine as well and came across this same problem which is more annoying than I thought. It sounds great as long as you stay under 3k. Anything above that will result in rasp and that dreaded buzz.
So I ask....
1. How do you get rid of the buzz and maintain this setup?
2. If this is indeed unsolvable, does an rtp clear up this problem? I fear of excessive drone if I take that route.
3. I've chosen Z1 test pipes. Could they be the issue? Does anyone have any input on ART pipes?

 

It sounds like you'll need to go with a resonated test pipe If you're very concerned with drone put your OEM cats back in.

 

^+1. Or maybe try RHFC. GL!

 

I've seen quite a few of your vids on YouTube and surely you have pretty much tried everything with your fi exhaust. I think you did LTH as well right?

 

Haha almost yes, I bought the LTH's but then sold them to a friend who has a similar catback to mine. The LTH was louder and more high pitched, the VQ hiss was a lot more noticeable too. I preferred the deeper tone of RTP's.

 

I'll look into rtps or maybe even just swapping the h pipe with a magnaflow x pipe. I'll make sure I post some videos of my findings as well. Bzzzzz!