Hmmm ... I stand corrected. The pink/red curves (11 discs) definitely look the happiest:

 

For those who do not like the usual supertrapp look but want to have its tuning ability, supertrapp offers an internal disc verison that you can install like a muffler and weld up a tail pipe to go to the center outlet.

It has a 4" diameter case and is 16 or 19" in length. They are available up a to 2.5" inlet.



It is the last one on this page:
http://www.supertrapp.com/Universals...universals.htm

 

>>This was a great post on the supertrapp. I am going to give this setup a try for my new cooper non-s. I do have a question sbout the disc-only section. If I only install that part, everyone says "loud". I would like somekind of db numbers to back-up the statement "loud". Everyones impression is different and I am curious on the sound loudness difference between the disc only and the trapp that brian is using. Do you guys think or have experience the noise increase?? Also would it be better to run a 2.5" pipe to the trapp over the stock pipe? I may have more questions but this is all for now.
>>Thanks

what about the disc ony version??

 

Why wouldn't it work to have a big straight thru resonator in front of the Supertrap, say where the Magnaflow or Milltek resonator is located, right behind the Cat. The kind of resonator I'm thinking of is sort of like a magnaflow muffler - a stainless cannister having a straight through perforated pipe surrounded by stainless steel wool. Then use the stock exhaust pipe back to the Supertrapp hanging out the back end a la Garfield, but using the 24" supertrapp instead of 17" one. Wouldn't that deaden the sound some and still allow adjusment of the backpressure for optimum torque and horsepower? What am I missing here?

 

I'm sure it would or could work, depending upon the application. I'm a ST fan, no doubt. I'm not running one on my MCS because the dialing-in of back pressure is not quite the option I was hoping it would be. It seems that the best, or most ideal power is with 8 to 10 discs - and that is quite open. And these were not with heavily mod'd engines, if I recall correctly. With an engine that is putting-out more power, even more discs would be desired. And that equates to more sound on top of an already loud system, by most people's standards. Given their size, they lack a lot of sound-deadening material, and rely upon the lack of discs to muffle or divert sound waves. Unless one wants to keep their engine output relatively tame, it seems that 2.5" ST might be either too restrictive, or too loud. A larger diameter might be the way to go though...

 

I measured the sound inside the car at 74 mph in sixth gear - 94 db

That's with the MINI Mania Header and a SuperTrapp with 11 discs

I'm taking the SuperTrapp off tomorrow and putting the Borla back on.

I set off car alarms when I drive up my street

I put some sound deading material in the boot and it cut the db's by 4 to 5 inside the car.

 

One of the several benefits of going with a ST is the weight-savings. The 24" one is like 5.5 pounds But there are some considerations. If indeed the tuning takes this up to 8, 10 or beyond (dics), then sound is an issue, subjectively, or possibly legally. Then one needs to add a few pounds of Dyanmat, or something comparable. Then the weight attirbute starts to be less and less advantageous.

I picked-up a Borla Turbo muffler (ss body, core & packing) at Summit Racing and it weighs 7.5 pounds, or the same as a ST with 2 pounds of sound-deadening material. So many wonderful trade-offs to ponder...

After chatting with more than a few guys, my approach is very simple - maximize flow, tune the ECU to your finished mods (UNIChip is nice for that), and add back-pressure if needed at the cat and/or with a more restrictive muffler. The ST that many of us are using is rated at a max of 250hp. While that may be so, it appears that it is much less if one wants something not overly loud...

As said before, and maybe earlier in this thread (I forgot), I think there are 3 factors in an exhaust:

1. Performance (objective - hp & torque, as well as weight-savings)
2. Aesthetics (subjective - the tip namely)
3. Sound (subjective - volume, as well as tone)
ok, price #4...

A ST was my first choice for quite a while because of my over-emphasis on #1. The looks and the sound just didn't do it for me, and I didn't care that much. But, when I started to see that the performance gains were problematic for what I wanted, I began considering other possibilities...

 

Sorry I thought you said supertramp

 

>> Given their size, they lack a lot of sound-deadening material, and rely upon the lack of discs to muffle or divert sound waves. Unless one wants to keep their engine output relatively tame, it seems that 2.5" ST might be either too restrictive, or too loud. A larger diameter might be the way to go though..."

supertrapp dyno secretary chimes in

the trapps we've been discussing here are the 4" disk size, which are good up to 250 hp. if you're really going over 250, you could use a 5" disk trapp. they are available with pipe dias. starting at 2.5." i suspect you could even start using the 5 incher with a 2.25" exhaust pipe.

here are some of my sound measurments, which are similar to dave's

http://66.220.28.159/forum/showthrea...ge=1&pp=15

i won't go back. the trapp sounds just right to me now; the stock cars now sound totally wussy to me....

(we need a smiley for this thread with earmuffs )

 

the link in the last post does not work for me, fire wall. does anyone else have a few sound clips from a cooper s with a trapp on it. im really wanting to put one on but i would like to hear what it sounds like.

 

bump anyone?