What some of the guys are mentioning here is the incorporation of the quarter length pipe.

Length of pipe needed = Speed of sound / (4*/Frequency)

*4 is the factor for the quarter length

What some of the guys are mentioning here is the incorporation of the quarter length pipe.

Length of pipe needed = Speed of sound / (4*/Frequency)

*4 is the factor for the quarter length

Typically, 28-30" of length for each pipe will kill a lot of drone from 2300-2900rpms. Mine are 28".

And I thought a banana in the tail pipe cured all exhaust woes.

Hello! Not to hijack a thread but...I searched google to fix drone in my Z32TT and somehow found this thread.

My setup is 3'' dp and 3''->2.5'' tp with 2.5'' Greddy SP exhaust. My butt-dyno is saying I gained about 30whp but I do have annoying drone at 2300rpm-2900rpm lol. I have to speed up to 75+ mph to quiet down drone.

Since exhaust diameter is different which diameter should I use for my setup? 2.5'' or 3''? Based on what I've read 28-30'' capped pipe sounds about right? Thanks in advance!

29" Capped tubes (one per side) at 2.5" each. The pipes need to mate to the exhaust at a 90 degree angle but the bends afterwards dont matter as long as the length and diameter are right.

Lemme know if that worked for you bud. :)

Cutting and welding sounds a bit too much... has anyone used Dynamat (or similar material) with F.I Catback to help kill the drone inside the cab? I could care less about it being loud outside =)

Just got this done today. But I was only able to squeeze in 20'' of piping because as you probably know already nothing's easy with Z32's. Well I thought I was going to go back to muffler shop but no need to. About 90% of drone is gone at cruising speeds. Just curious now is there any performance loss with this? I don't mind sacrificing 2-3whp for quiet cabin.

Here's my progress for reference.

https://www.300zxclub.com/showthread.php?t=202092

Thanks for your help.

;)

Glad it helps! I am surprised that 20" helped but thats definately cool.

Just wondering, how long did the install take and how much did the shop charge you to do this?

so is it possible to fit a 12 in resonator on there?

Install took about 1.5 hours and cost me $220. No performance loss.

Another thing you guys should look into is widen the diameter for these helmholtz pipes. It covers a wider range in the area of where the drone occurs

Hi to all!

I went to do some experiment rite aft I read this post, because my muffler drone like hell at 1300-2500rpm!! My pipe is 2-1/2 inch and I had a 2" pipe weld side by side with the main pipe with the length about 1.3 meter. Unfortunately, it still drone at the same rpm.. is there anything else I could do??

Thx for the help!!