I have a Cattman 3" exhaust w/ headers, and I love it.... the only problem is that there is pretty bad highway drone between 2200 and 2600 rpms... which is worse because I drive a 4AT. I've heard putting sound deadener in the spare tire recess helps... but where else would be good to put the stuff... keep in mind that I got it from a friend and only have about 30-40 feet of deadener. What would be the best way to cancel out my drone with this amount of sound deadener? Trunk floor?
Thanks for any help.

In the area over the muffller, and in the recesses over the right side would be good areas to start. It doesnt bother me that much, but i have an extensive stereo so my entire turnk is done. You could also focus more on the passenger area to keep noise out, but i would begin over where the noise ic coming from.

You could look to liquid deadener as well to kind of...stack against the noise as sludge type deadener is a little esier to build up levels.

I've tried a sheet of RMax insulation in the trunk and it helps a little.....The main source of the sound amplification is the spare tire recess which will be dynamat'd in a few days.....I'll also cut a piece of plywood and cover both sides with a sound deadening quilt and maybe some dynamat between the rear muffler heat shield and the trunk underside.....I'm just trying to change the frequency in that 2200-2500 rpm range....to reduce the low speed drone....Which is'nt real bad but noticable....

First step: Buy yourself a big, chambered resonator to go inline with the other one. That'll get rid of the drone a lot more than sound deadener will.

Add sound deadener after...

Yeah but that would probably defeat the purpose of having a 3" exhaust in the first place. Is the muffler on Cattman's 3" chambered or glasspacked?

If the inlets and outlets are 3" OD, though, I don't see it restricting exhaust flow terribly. It'd be no different than running a 3" exhaust and then slapping a Flowmaster on the end. Cattman's muffler is resonated. I dunno about the res.

Most of them, even though they're chambered to reduce noise, are pretty free-flowing. You won't ever be able to get rid of drone with glasspack parts, unless you maybe pursue a resonator the full length of the exhaust.

I don't want to tamper with my 3" catback construction the drone it's that bad!!!! Just trying to quiet the exhaust resonance @ 2200-2500 rpm a little...I actually have a secret little piece that will lower the sound by 10db's....I do have a 20" resonator that was part of the setup.....I love the sound of my 3" exhaust,.... it's just that part throttle acceleration thru to 2200-2500 range.....that I'm trying to lower the decibels....

Interesting thread.... on my stock maxima ... i have a full roll of Raammat... a layer on ensolite foam and Mass loaded Vinyl on the entire floor pan, rear deck and all doors.

Raammat and ensolite on the roof.... and Raammat and carpet padding in the trunk area.

Now if only I could get rid of that darn wind noise!!

As for engine or exhaust noise... i only hear it north of 4500 stock exhaust though.

Perfect for my cross country trips.

My suggestion would be to look for some mass loaded vinyl... any mat is only a vibration absorber and if you want to really block that bassy sound.. mass loaded vinyl is the way to go. I wish you were closer, I could have given you a piece from my left over roll.

A lot of the wind noise can be subdued by packing open-celled foam strips in the rear window seals. Just pull them down, pack in the padding, and push the seals back on.

Housecor's site, shiftice.com explains it in more detail...

crazy thought...get rid of the catback

isnt like there is a performance gain...the only thing you are getting is noise...that you admit you dont like

wth is wrong with you lol

different with the 3" catback, there is power to be made with it...about 12 horses to be exact.

I agree with SLP...another resonator would help...your not going to hurt anything by adding.

If you are gonna do the sound deadening, trunk floor and rear deck

I tossed one of these bad boys on my old set-up when I removed the cat and didn't like the noise.



3in in 3in out, center outlet. this will do more for sound vs a glass pack or resonated core (forget the louvered core). I didn't see any loss of airflow on the MAF side when I tossed one of these on, though I did when I used a louvered core.

We can sit here and argue all, or most of the day about defeating the purpose, etc, but keep in mind, anyone with a fast cat and Cattman headers, they are both a supposed bottleneck of 2.5" pre-catback.

^ Where'd you order that thing from? And how well did it kill off the sound? I might grab one and toss it inline with the wimpy, awful res I have right now.

According to Moroso it flows 850 C.F.M and kills 5-7 dB's. It got rid of my rasp I got with a test pipe with my previous set-up. If I am unhappy with the noise level of new Cattman, I may get another, since my current one id on my old cattman b-pipe is, which is 2.5" (yep, I did it, kettle black)

I got it from Summit. 95$ for the SS version, $51 for the natural version, shipping is extra.

I would have thought putting the sound proofing under the console (tunnel) would be the best place,

You're speaking of the Spiral muffler? Oh yeah my bad I didn't see the illustration!!!!How do you like your Cattman 3" catback by the way?

Hence why I made my headers into 2.5" collectors into the y-pipe and a 3" at the y-pipe coupler and then 3" all the way out.

That's what sparks did too, sorta, lost that equal length business though. I kinda like my cattman right now It might annoy me later, but past 3k or wherever, it's awesome. And also, not sure if it makes a difference but ahh, I have nothing in my trunk, no spare/carpet/nothing. A pair of jumper cables and a cross.

Where can we find affordable mass loaded vinyl though? links?

Or you could just do a loud stero and not worry about exhaust! lol
But i think sounder dender. in the turnk would probllay take caar of it just fine

I bought some sound deadener and luxury liner pro to help with my drone, unfortunately they are still in the box. I'm pretty confident the LLP will get rid of most of the dreaded drone.


I also have problems with my 3" rattling on the rear suspension...anyone have a fix for this?

Here is the site I bought mine from.
http://www.soundisolationstore.com/p...-mlv-1-lb.html

Great guy to work with, responds quickly.

I did the following areas:
- All doors.
- Complete floor pan, this involved removing the front seats and getting the mlv under the carpet. Removed the rear seat bottom and laid it there.
- Under the rear deck.
- Removed B and C pillar trim and put it there too.

All this time folks would do the mat and foam treatment, but it really did more vibration absorption than noise blocking. MLV is a real sound blocker. You need to use it with a closed cell foam like Ensolite from Raammat or something from secondskin etc. That way you will attack both low freq and high freq sounds.

- I am still wondering if I want to do the trunk. With the above the car has become amazingly quiet. My max is completely stock and the noise levels I used to hear at like 55mph are not heard at about 75!

The only noise I now have is wind turbulence but that is something you can't avoid even in a 7 series I might be able to reduce that a tad bit more if I can get my hands on the acoustically insulated windshield from an I30.

readjust the RM, by loosening the clamp and the bolted in hangar bushing, and adjusting more than likely engagement of the slip fit joint with more penetration....

I don't think the peel and stick liner is going to help the drone to much because the drone is a low frequency tone and most of the dynamat type deadners are designed to stop metalic rattiling like sheet metal viberating I suggest if you can to isolate the area around the exhaust with some high temp fiberglass insulation made for automotive use they used to sell it at summit

Like adding a muffler AROUND the muffler. I Wonder how the OEM A33 rear section would sound with the rest of this system

IBbasterdizingsaidsystem

this is what I am using, although I havent installed it yet. There will be a layer of sound deadener laid first, then Luxury Liner Pro.

http://www.secondskinaudio.com/noise...-Liner-Pro.php

That is seriously overpriced for basic 1lb/sq ft Mass Loaded Vinyl.

Look online for cheaper options!

It is pricey, but for the reviews on it, I couldn't find a better product. I want to do this once and never worry about it ever again.

Maybe you could post some links to mass loaded vinyl so these others guys and myself could know about it in the future.

Look up a few posts, I've already posted what you're asking for

Mass Loaded Vinyl is just what the name states... one calls it luxury liner ... I call it sound blocker.

Secondskin is a brandname. Yes, initially when it was new, their prices were awesome. I bought mat and closed cell foam from him to do my 330, but recently their prices have jacked up quite a bit.

Mass loaded vinyl is available for construction. It's uses include theaters, office setups and homes for creating sound barriers in the walls.

About doing it once and not bother... that is highly questionable. Its something you are sticking on. On the floor pan and rear deck you should be ok, but over time there will be chances it will come undone in the doors. Here in FL I have seen dynamat extreme come off on cars that are routinely parked outside. I'm lucky I garage my max.

For really good sound deadening in addition to the MLV... I strongly suggest the secondskin spectrum sludge. I have it only in my wheel wells and it cuts off tire and road noise to the max... if you have to do a bang for your buck application do that first. Most of our cars are now nearing 10yrs and if you notice, the OEM sound rubberized spray on the underbody is now probably chipping, coming off or almost gone.