SuperTrapp Discs
 

Preliminary report:

This kit is the diffuser discs only, intended to add onto the end of a tailpipe. After I got around to messing with it, I saw a couple problems right off the bat. The nuts seem to be the wrong size thread for the ss bolts. The bolts themselves are small diameter, and don't look like enough to support the weight of the discs (under hard road use) once the thing is assembled. The kit only came with very general instructions, so I had to hunt some down online:

http://www.supertrapp.com/resource/faqs.asp#17



The kit also has an optional black shield that deflects the exhaust toward the back of the assembly. Now I would have returned this kit, but I had a flange welded onto the inlet before I got a good look at the hardware and all. I got some ss couplers to use instead of the mismatched nuts thinking that would make the whole thing more sturdy and less likely to have bolts seize up.

The intention was to be able to run it on the way to the track, then remove it for racing. But right now I'm not too enthused about trying it at all, since the Borla "resonator" is in place and sounding decent.

This is pretty neat. I never heard of these things. Where does it mount? Right after the down pipe?

No, at the end of the tailpipe. This is what the full mufflers look like:

haha, that's crazy. Looks weird though.

these were big in the late 80's, early 90's. A lot of Pro-Street cars were using them.

I want that Vista Cruiser!!

What is the benifit? Make the car quieter to drive on the street to the track?

Backpressure
 

I will try to keep track of how much backpressure these items contribute, and how that relates to the noise level. Today I put a pressure gauge on the exhaust system, tapped into the EGR port downstream from the front header bank. That will give some idea of the total system backpressure.

The baseline system is TOG headers, 3 inch CAT, 3 inch Borla muffler as resonator, and 3 inch Magnaflow tailpipe muffler, all mandrel bent tubing. At WOT, the maximum pressure reading was 4 to 5 psi and stayed there for much of the powerband.

So the next step is to remove the Magnaflow muffler and do a retest, at the risk of annoying the neighbors.

Annoying the neighbors is the fun part.

I don't have to worry about that up here... we compete for loudest vehicle!! hahaha its great!

My Delta will have basicly a straight pipe exhaust, well straight X pipe duals.

Headers to non-cats to X pipe, to Dynoflos to exit right in front of the rear tires. Damn it's going to be loud :D

Its going to be loud but it will sound awesome.

Moving along, I removed the Magnaflow muffler and tested, leaving the headers, CAT and Borla. The backpressure dropped only slightly, maybe by 1 to 1.5 psi, or about 3.5 to 4.5 total backpressure. The sound was much too loud, though. More than the Magnaflow w/o the resonator. That I expected, but the quality of the sound was not good, bordering on obnoxious. At least from inside the car, windows down. I don't think I'd run it that way at the track.

Next, I added the disc assembly to the tailpipe and retested. This time, the sound was much quieter than the baseline system (CAT-Borla-Magnaflow).
Unfortunately, the backpressure increased by a factor of two, I now got 8-10 psi @ WOT, and 2-4 psi when nudging it into boost, 2k-3k rpm. That is not acceptable. The long bolts supplied with the kit will allow more discs to be added. You could double the number of discs if you wanted to, but extra discs are not really cheap either, and no doubt would be louder. I did kind of like the look of them installed, and the weight was only a couple pounds, about 10 less than the muffler.

I'll bet nobody can tell what vehicle this muffler hanger-bracket came from (hint: made before most of you were born ;) )

Hey what's the dealwiththe "off on"

It's his toy car

lol... hey, remember when they had those "joke" wind-up toy crank keys to put on the back of VWs ?

Added another 12-pack of discs (part#504-6512) to the assembly and did a road test, and it was louder than the 12 discs, but still not as loud as the straight-through system. The sound is a different type than typical mufflers, for sure. Snarling, growly (gnarly??) sound, but not really raspy. I kind of like it, actually, from inside the car. Can't say what it's like from outside.

You have to pay attention to aligning the discs and not overtightening when assembling to get an even spacing between them. After testing on a hot day and getting what seemed like too much backpressure, I reassembled it and retested on a cooler day. That time it did better, but I don't have any real numbers for backpressure yet. I would like to add a couple more discs, yet I don't want to pay for a whole twelve pack. I'll watch eBay.

I love the time machine!! Such a sweet car!

Yeah, with a rear-engine 455, it handles great, too. Don't know if Bob still has that one. He was definitely an artist with the old-school paint themes.

Yeah it's been awhile since I have seen it but I always loved it when he would bring it to the shows!