What makes a Quiet and free flowing exaust

[sydneymk1]

my 16v mk1 is running but im not one for loud exausts i want a quite and of course as free flowing exaust as possible. im using the standard exaust manifold and twin down pipe
the Benzs i used to work on even the amg models were all very quite at idle i think it was due to the thick stainless exaust

has any one had bought extractors and exausts that they would recomend or exaust shops in sydney recomended

approx prices normal and stainless

[Oneofthegreats]

For a NA 16V I'd go for something in the 2.25" size piping with a centre hotdog (resonator) & a free flowing straight through offset rear muffler. If it's still to loud, through on a twin bypass rear muffler.

On my Mk1 GTI I have a set of 4-2-1 extractors, straight through 2" piping with a centre hotdog (can't remember how long it is) & straight through offset rear muffler with 2.5" tip. Not too bad on cruise & light throttle, but when you get into it, it opens right up.
Also rear tip size & angle only can dramatically change how loud your car is.
I've had the same systam as above with a 3" rear tip, a 2.5" dump pipe & DTM style & they all changes how it sounded from excessive dronning at cruise or being tinny up in the top end.

On new car's remember that they run cat. convertors, balance pipes & also very large (& most times very restrictive) capacity muffler's incl. twin chamber muffler's & mutiple pass muffler's.

Eg. a BMW E46 M3's rear muffler has a capacity of 130+ litre's.

[finemk1]

hey im running the stock manifold with a twin downpipe, to a flex and the 2&1/4 pipe all the way with 2 resonators and a straight through free flow rear muffler, its was measured at 106 db at 4000rpm and 96db at 3750rpm which is right on the limit of legal if you have good pursausion skills. ive had a few different mufflers on it it and found anything that isnt straight through was restricting noticable power so i just use a removable baffle in the tail pipe which works well for the noise. if this dosnt tikkle your fancy and dont mind a tiny power loss then id change the rear muffler to a twin bypass or similar like golfwox said..

[gldgti]

i've mad a few exhausts on the diesel, and now the same ones on the petrol...

the standard twin downpipe with a bigger exhaust back seems to be quite noisy. my diesel had that, with 2" straight back, straight through muffler and a hotdog halfway. that is one loud exhaust.

by contrast, the 4-2-1 extractors with 2.25", very small resonator and large straight through (offset) rear muffler with 3" flattened tip is quieter in the criuse - more power too, both on the petrol and diesel.

i think like the guys said, as large a rear box as you can fit will cut down the noise.

[smithy010]

Does a hotdog make it sound louder?

[Fizz]

I found and has been verified by a good exhaust dude that those bullet (hotdog) resonators increase the droning sound u get in the cabin when cruising. I think a straight 2.25 inch piping from headers mated 2 a as large as possible rear box as echoed by everyone else.

My GTI has a straight 2.5 inch turbo back system with no resonators or cats hooked up 2 the Stock GTI back box. Its extremely awesome and undercover as its quiet on idle and cruising but roars when you blip the throttle or put your foot down ;)