chewy8000

85-86 manifolds, Y-pipe, RMB. All thats left is the small stock muffler and catback pipe. What are my options? Will a single Borla muffler be quiet enough to weld in place of the stock box or do I need the whole catback system? $500!!! for the catback is way outa my range. Any used ones out there?

AO

If you can fine a borla (I remember seeing that they don't make one for the 928 anymore), I'd put that on there. They sound great on the early cars.

jleidel

The Borla system has a nice fit and finish... with nice pipe bends. I don't see why you couldn't grab the bare muffler with the correct sized inlets and outlets and have a muffler shop weld it in place.

Drewster67

Replace the RMB with a magnaflow or a 3 chamber flowmaster. And then sell the RMB

Jadz928

On a very simlar setup to yours, I used a single Borla Sportsman muffler. Here's the specs...

Very loud and "Camaro like", as you referred to it. My specs show a 2nd Borla bullet muffler but it never got installed. I was on my way to have it installed when a milk-truck pulled out in front of me.
I was hoping that would tone it down a touch.

The Borla cat-back system 928 Intl sells would work nicely with what you've done up front. It's a different type Borla than what I'd installed. I know two 16V cars quite well, both with the Borla cat-back (+headers) and they both sound great!







<----------------hey look, 928!

Mongo

Dynomax has a pretty innovative muffler that has a bypass valve inside of it actuated by a spring where exhaust gasses will bypass the final chamber on WOT. Only then would it be loud, other than that, it's as quiet as the come.

PorKen

I wonder how they stopped that valve from clattering at low rpm?

I tried something similar. Exhaust pressure builds, the valve opens, then shuts quickly.

It looks like they offset the axis of the flap, and kept it partially open.

SMTCapeCod

I have one on my Volvo. THey use some ceramic wrap around the holes for the pivot-rod, and I think on the edge of the blade now too. Not sure what the resiliency will be-- especially that tension spring. But I've run it for a year now through summer and winter and it still works. It does sound like a sedate turbo muffler at idle, not as quiet as stock.
Of course, pressure moves the valve so the penalty of dual-purpose is some pressure...on my volvo it doesn't matter much since there is a turbo upstream to begin with, doubt this introduced any additional lag beyond the stock muffler.
Would I install one on a 928? I'd like to try/hear it, but until that falls in the fun-money category or else I find more hours of tinker time, I don't think so.