a quick observation on exhaust systems.

[Dr. Diesel]

I was running a techtonics tuning 2.5" with 2 resonators and no muffler. It was great. Over the last couple months, more and more,  I've found it too loud. I don't know if the packing has blown out of the resonators, or maybe their little perforations have been carboned over, or what. Anyway, in an effort to hang on to the last scrap of my sense of hearing, I had a muffler installed. I used a 2.5" (duh) dynomax super turbo muffler. I've always been a huge fan of them, they sound awesome, not too loud, last a long time and are reasonably priced.
So the exhaust shop did a great job on the install, they also replaced the mishmash of  bits n' pieces that connected the downpipe to the TT centerpipe and muffler eliminator pipe that the last guy ended up using when he discovered that he didn't actually have a stick of 2.5" AFTER cutting off all my old stuff. (arsehole)
The results:
It went from way too loud to very quiet. I can actually hear the engine noise, and the turbo inlet sound. Before, the turbo would howl and scream out the exhaust, and idle with a very cool rig-like whistle. that's very faint now.
So, mission accomplished, or overaccomplished, as it is.
The last super turbo muffler I had dealings with was on a 96 gas 2L golf, no resonators, just the cat. It sounded great.
Confusing that what was so loud could be so muffled.
Anyway, i'm pleased to report that there's no noticeable drop in performance.

[lord_verminaard]

The Converters must do a good job of muffling the exhaust, as I just took my gasser Rocco for an (illegal) spin around the block, it's got Autotech headers, TT 2" exhaust with dynomax and resonator, but no cat.  It sounded ok under 1/4 throttle, but open it up and it wails.  Loud, but cool.  I'll need more road tests to really decide if it's too loud or not, but I was suprised.  Especially since it's a stock 1.8 JH with 8.5 compression.   :roll:

Brendan
84 Scirocco 8v
00 Camaro L36 M49

[fspGTD]

I've had experience with Dynomax super-turbos.  They aren't the best flowing mufflers available (their internal flow paths make the exhaust gasses take an "S" flow path through the muffler - reversing the flow twice).  But for a non-straight through muffler, they also aren't unreasonably restrictive.  I think they are well suited as a performance muffler to a naturally aspirated VW diesel.  Or like you said, a "really quiet" turbo diesel.  But I'd be surprised if it didn't cost a little bit of performance on a turbo application.

I ran an Edelbrock RPM series muffler in my Rabbit GTD 1.6lTD (2.5" in diameter.)  The muffler is 409 stainless and a bit more pricey than an aluminized super-turbo, but at about $80 I think for something that will never rust out, still a great value.  It really worked well with the GTD when I was daily driving it; and was very quiet - I think muffling about as much as anyone street driving would practically need.  I also didn't find a problem with it getting louder over time.  That was with no resonators and complete 2.5" exhaust system.

Since removing the muffler from the GTD and having the GTD gone dedicated autocross duty and mufflerless, the Edelbrock RPM series found it's way onto my daily driver nissan maxima (I know, ick!  :oops:)  Anyway, with that muffler on the max, it's a bit louder than a stock muffling system, even though it still has a resonator and stock cat.  

Dad's Rabbit, the '84 naturally aspirated 1.6D, had a very small resonator and super-turbo in a 2.25" system size.  It was actually kind of borderline loud!  I'm sure adding the turbo is going to quiet it right up though.  

Naturally aspirated applications definitely require more muffling than turbos!

[Hammy]

When I was still running my n/a motor, I had a 2" system from front to back installed with a dynomax superturbo muffler, and it was loud. Then I swapped engines to the turbo, and it was quite quiet, just like you described Dr D. I guess the turbo just takes alot of noise out of it.

[PYRO]

I've got a 3" GHL Turbo Back on my 1.8t and it sound AWSOME it's loud but by no means over powering or annoying, it has a high-flow cat small res and a straight through muffler incase you wanted to know

Jay

[Rat407]

I've got a 3" GHL Turbo Back on my 1.8t and it sound AWSOME it's loud but by no means over powering or annoying, it has a high-flow cat small res and a straight through muffler incase you wanted to know

Jay

Where did you get the cat? I need to keep mine but it is shot and I don't want to pay the cost of a new one at the dealer, not to mention I want a larger one on there. Darn emissions around here, who would have thought an old diesel would have one, but Nooooo VW had to go and put one on.