Went in for my Warrent Of Fitness yesterday and failed at 97 decibels. I have already tried a couple of things to quieten down before I went in.
FD. Running full bridgeport, single turbo, I have a 3" with a small midpipe muffler that is 2.5" & a rear muffler about 600mm barrell also 2.5" ID ( both mufflers are new from adrenalinr with stainless and ceramic fibres.
Any way to quieten without chocking the Hp out of my car.

 

Steel wool in the mufflers seems to work well for some of the motorcycles in my area. Of course it is something you only want to do to get through inspection. That is the only thing I can think of.

 

dam that sux, did you take it to a VTNZ?

 

not in delaware....

 

This might help

http://www.youtube.com/watch?v=UeMwINlHaPc

http://www.engineceramics.com/hardpart/ccinserts.htm

 

the OP is from new zealand, same as me
VTNZ is vehicle testing new zealand

 

I have a small turbo and no bridges, in my 12AT. Mine is quiet as some pics for your reference. full 3" from turbo back. That is just the biggest rectangular drum muffler that would fit. Interally it has 1 mandrel bend and is offest in, centre out. I believe it is like 10" x 8" and 20" long.

I'm catless and full 3" no problems with noise here.

That is a cheap truck muffler, you just need more muff!!!

 

I went to the local dodgy warrents & co. but they gave it a pretty good going over. I like the look of the cc inserts but I'll have to have a hunt around and see if anone sells them in NZ.
I like the steel wool idea, but need something more permanant. I tried one of those silencer reducers that sits in the tip of the muffler but had trouble riveting it in so only got one rivet through. Tried to start the car but it didn't like it much, it backfired and shot the insert up the drive then started no worries.

 

^ You only need it to pass inspection right..? I dunno what you have to deal with in terms of law enforcement and how strict they are. Liek do they give you guys inspection tickets if they think your car is not street legal..? Here you only go through inspection once every two years. Put some steel wool in the muffler and secure it until you get through inspection, then remove to enjoy your vehicles previous Db level and bust down the main strip again.

 

large resonated midpipe + 5x14" round magnaflow muffler + 5x8x18" dual magnaflow muffler

all 3" inlet/outlets with straight through design (except last muffler which is 2x2.25", in hindsight should have gotten 2x2.5" since 2.25" looks weird




+ resonated midpipe

 

How did they test the noise on the exhaust OP. There are rules in NZ around that.... for example needs to be done in an open field with no walls around etc etc..... if it was done in a garage or near walls, 7db would be very easy to gain on a meter. I suggest maybe taking it somewhere else that isn't as strict on noise. (I can recommend a guy in Auckland if you don't mind the drive)

 

^ I missed how they took the test. I've just got my car back on the road after some major work & is noisy enough that I am embarrased to drive it.

I have just welded in 2 borla mufflers back to back in my mid pipe, looks like MIBagentQs' bottom photo but with a division in the middle. Now I can't start my car ( flooded ) will have another crack tomorrow.