Mine was made by Paul Anderson of 928spares.co.uk in the UK.

If he's not sure which rear muffler you mean, tell him its the one he made for Joel Hopwood's 87 S4.

No idea on cost - I got it with the car.

 

It can be done and will be done on my car sometime this winter. I'll post pictures when it is done.

If possible, i would like to market a product for the 928 group.

jpc

 

Here's another off the wall rear muffler idea. This is a bit ricer for an otherwise stock car, but some of the loud (in terms of overall appearance as well as exhaust sound) modified cars might use the following. It certainly would give a unique, modified look.

Use Borla's marine racing exhaust muffler as the rear muffler. It's 4 inch inlet and 5 inch outlet tip. The 5 inch tip would probably fill out the cutout in the rear bumper cover nicely. One wold need to fabricate the y-transition from dual whaeversizeyouhave exhaust pipes to a single 4 inch.

http://www.performancemotorsportsnew...rla_marine.pdf





The muffler is 12" long, so it would probably fit the space for the 928 rear muffler.

 

I think our pipes dimensions are about 2.2 inches inlet. I have found a muffler with an inlet of 2.5 inches. While i am sure anything can be done i am going for more of a basic muffler. The borla muffler will be VERY expensive. One of the most popular
911 exhaust companies Bursch uses Dynomax as their muffler. I am using a muffler with better quality than Dyno.

Anywho...its a good looking muffler, i do wonder what it would sound like.

 

I think Dynomax is in fact one of the best mufflers out there. This judgment is based on the fact that unlike almost all other muffler makers, the publish the specs of their mufflers. You can for example back out the CFM @ 20" from their power ratings.

The price range for that Borla marine muffler is huge. Small shops sell it for huge money, summit for half that. And I think the kit price is for two of them. Still not cheap, at least not yet.

W/r to the pipe diameter, I've got dual 3". The slash cut pipes don't quite fit in the opening the best possible way. A single tip would fit just right. It's also that without a rear muffler, the dual 3" system may simply be too loud for our little cul de sac of suburbanites. So a rear muffler of some sorts may be in the cards. I'd like to stick with Borla for the rear muffler since the other components are from Borla as well. Otherwise I'd go with Dynomax.

 

From the research I did when I had my 1986.5 track car, I found that a single 3.5" exhaust would be perfect for my applications and that it would support north of 350HP from a normally aspirated engine. It kept the torque of the engine too.

The single pipe set up was tidier, lighter and mixing the two exhausts makes the car sound very nice and mellows out some of the raspiness . Always had great comments from bystanders at the track about it's sound.

IIRC, 928 Specialists had single exhausts designed for the 928 that looked very well made. Don't know if they still carry them.

Of course if your running a boosted engine, or a stroker, then bigger is better.

Cheers,

 

For NA, the firing order, headers, cats vs no cats, cross-over location, etc. all matter so much that it's basically way above my pay grade.

For a turbo engine, such as mine, it's much simpler. Turbine garbles a lot of the pulses so pulse tuning is not very relevant. (There's an exception of low-boost, high wastegate priority exhausts in boost limited racing classes, but that's a digression.) Make it as big as what fits, or bigger, and add mufflers until the neighbors stop throwing objects at you. I am not quite there yet, I am afraid.

 

Ok i like the dyno max mufflers, they are great value for the dollar. I was told by a welder that there weld joints are not as good as the other muffler i am looking at. He did say it was a good muffler and i have used alot of bursch muffler in the past that sounded awesome. I measured my OD for the inlet while the standard muffler is still on and it measured 2.2 inches. Maybe it was 3.2 inches. Maybe my memory is fading LOL

 

since it is already loaded here from the past this is what I have - 2 of them;

(the cats do the real muffling)

moroso in steel or SS

 

Wait...so someone wants a straight-through muffler...then installs a flap to impede flow that is held with spring pressure...in an environment that is subject to condensation and fairly extreme temperature fluctations....bad idea. I can buy tinkering with some of the options that have a vacuum operated valve, but one that uses backpressure...nah.

I used to have a bead on an aftermarket builder that made such a system for classic apps, but I'm not having much luck locating it.
At the other end of the spectrum: http://www.bbexhaust.com/car/corvette/fusion/

 

They give some sort of a warranty on that muffler.

I agree in principle about the back pressure, but I guess we'd have to know how much restriction the flap will cause when at WOT.

So what's your view on the X-pipe-muffler combination that Dynomax brought out recently?

 

I think we tend to get amped up over a few HP/TQ differences between H and X pipes...and then the particular location and design of the crossovers...Good stuff for track cars but likely pretty inconsequential on the street

So, actually, I like the idea of the Dynomax X-muffler combination. ...The generic 'x' design isn't as optimized as the units created by some in the 928 community specifically for our cars, but it's probably a good 80% solution...but the crossover really only makes sense up front if the goal is to equalize the pulses from the cylinders. It's actually filling a void left by the same design that Magnaflow came out with about 8 years ago then discontinued...At least I thought they were discontinued:
http://cgi.ebay.com/ebaymotors/Magna...item5ada8a7688
I bought one of those with the intention of fitting it in place of the factory cat(s), much like the OB RoW front mufflers. Here's a similar one without the packing:



In the end, I had a custom muffler designed for that purpose...but it ended up under my V8 A6.... and I stuffed the Magnaflow with the internal X under my GTO to take the edge off the drone that came with headers and change from dual OEM cats (per bank of cylinders) to Dynatech high flow units. Did a nice job of tempering noise while cruising, while still allowing a good bellow at WOT. Too quiet at idle for most of the Goat crowd..but all depends on what one is aiming for. For my part, I don't think open, unfettered exhaust is warranted except for track cars or street rollers putting down something North of 450HP...but that's just me.

Surprised no one has a kit yet that uses a crossflow design like the old F bodies, to provide tips on both sides of the car. I guess hacking that rear bumper cover is not anything that would generate a lot of interest (hopefully)! IIRC someone used a dual-exit muffler and ran a pipe over to the pass side..it was sketchy though.

 

Perhaps this is what you mean by a crossflow design close to that of the old F bombs:



I wouldn't mind having symmetric dual pipes with mufflers at the end.

For the visuals, I guess one could have a single muffler at the place of the stock rear muffler that would have two exits, one which would go to the right side of the car.

The bumper cover I could hack, but the fuel tank is a problem.



How would you navigate the fuel tank to provide a second opening similar to the stock exhaust pipe cutout? I think one would have to relocate the fuel pump, at minimum.

 

my memory could be faulty, but I thought one owner- quite a few years ago, snaked a pipe over to the pass side.

On the GTOs, the 04 tailpipe is configured like 928s, and then 05 -06 had dual exits. One company makes a bezel that is fit into the bumper cover of 04 cars once the pass side exit is cut in-- looks great when done. But there isn't the obstruction issue to work around.

Could do something a little different by using one of the electric exhaust cut outs, and tying it to an rpm switch or throttle switch to channel exhaust between a muffled/cruise system and open/performance system. Mitsubishi did this with the VR4 (system on right)- 3" center into 2.25, IIRC:


It would be tight with the two pipes side by side for the existing exit..and really this is imagination running amok because your 'Plan A' was a much more practical notion.
If you do it, I hope one can be configured for 86.5, too...

Carry on!

 

This isn't quite as impractical for me as it first sounds, because I will already have to run a pulse-width modulated signal to the back of the car to control the fuel pump. I'll be using the MAF analog signal converted to PWM. If there are exhaust valves that operate on a PWM signal, that would work. This exhaust-valve mod is not on the top 10 things to consider, however.