porsche928guy

My 85 car has Carl's true dual system on it with RMB. It had the factory cat on it and the system sounded really nice (actually liked it better than the Borla and Y system on my 82). Anyway I put an X pipe on and now it is WAY too loud. I've been looking into different cat options as well as combing over the exhaust threads on RL and from what I understand the metal matrix cats are far superior to the ceramic. Unfortunately those are out of my price range right now. I've come up with some possible options to get me by...what do y'all think?

1) Take out the X-pipe and replace with factory cat until I can throw money at some good cats

2) Take out Carl's system, sell it, and have a new system built that uses larger mufflers

3) Throw a generic ceramic cat on for the time being.

4) Add some mufflers somewhere on Carl's system (maybe some small round mufflers just after the X) or replace the current mufflers with larger ones. I'm not too excited about this option as I'd rather not hack up Carl's system.

5) Open to other suggestions...


I'm looking for a nice mellow sound but right now it sounds more like an 82 Chevy truck with blown out mufflers.

Tampa 928s

Can you put the pumpkin back in if so, open it up and cut out the machine gun looking pipes, then weld it back up. I have no cats x-pipe and it got me a ticket after doing the pumpkin carving its perfect.

porsche928guy

No pumpkin...it was gone by the time I got the car but I'll keep my eyes open for one on the cheap to try that out.

Abby Normal

Remove the RMB and add a MagnaFlow on the back. I have my track car set up that way and it sounds hella sweet!

SharkSkin

I've heard the Random Tech cats are good for maybe 10K miles... Hardly seems worth it if you want a cat to stay on longer than it takes to inspect the car.

How about another option:

6) Roll up the window

sharknoob

+1 on taking off the RMB.... I just got a Flowmaster 50 series delta flow muffler to fit in there from Summit Racing for 80 bucks I think

Cosmo Kramer

RMB stands for rear muffler bypass correct? I thought Carl's system has 2 mufflers in the middle of the car as per this pic.

What does your system look like? If you have no cats and the muffler bypassed, you are basically running a straight pipe.



What does your system look like? If you have no cats and the muffler bypassed, you are basically running a straight pipe.

Mike Frye

Ted,

That 'pumpkin' at the end of the one on the left is the second muffler. On the right you see the pumpkin is missing and 'bypassed' with the RMB, but it's still got the mid-mufflers, one for each side.

The stock setup has a mid and a rear (2-into-1-into-2, twice), Carl's (and anyone with an RMBs) only has the mid-muffler in place. The cats need to go forward of this, usually between the crossovers and the appropriately named 'cat-back' system .

Mike Frye

I think that would defeat the purpose of the dual exhausts though, because the pumpkin combines the exhaust. I'd say to try the Borlas on there or sell the duals and go back to stock. No sense using the duals with a stock rear muffler.

I wish I could swing it right now, I'd LOVE to put those duals on my car, but I already blew my annual Shark Splurge this year on other stuff.

Cosmo Kramer

OK gotcha. Interesting that it is that loud seeing as the stock system had the small mid muffler and the "pumpkin" with 2 pipes into each one and Carl's has a separate muffler for each pipe. You would think they would be somewhat equal but I guess not.

That true dual is on my wish list too, just no cake in the shark fund right now.

porsche928guy

Hi all...yes Ted the system I have is the one on the right (actually the one pictured is quite possibly THE very one on my car). The RMB is simply the black portion of the exhaust that replaces the pumpkin. Anyway it does sound VERY good with the stock cats. I removed the cats and put up an X and now it is way too loud (even with the windows up Dave).

I was thinking about putting one of these 4'' round magnaflow
on each side just after the X but concerned that I won't gain much sound dampening and again not too excited about hacking up Carl's system. Anybody have experience with this type of muffler?

Cosmo Kramer

OK looking at your sig you are supercharged as well. You have some serious flow going on which is probably not helping in the volume department.

What kind of mufflers come with that system? Can they be removed and have something quieter put in? If you go to a good exhaust shop, they should be able to weld in something nice and keep it looking neat.

porsche928guy

Ted...I'm not sure which mufflers are on that system but they are pretty small. I think I'm going back to the stock cat for now before I get a ticket and I'll figure the rest out later.

sharknoob

I doubt you would even notice the difference with that magnaflow on

MGW-Fla

On both of my '85s, I removed the cats & installed an Xpipe, left the rear mufflers alone. Sounds great to me, as a 928 should sound. Wife thinks its too loud for her though, but she has her S4 to drive which she likes stock.