Thinking about a new system for a Saab 900. I had a GPz-1100 once with a Kerker header & muffler; the muff was stuffed with fiberglass. When the 'glass went south, it got louder but with a definite decrease in performance, mostly at the top end.
Saab 900: Keep the cat, 86 the muffler and put a resonator or muffled tip at the end. Thoughts, experience?
No one should be surprised that I am an adamant defender of Conservative values when it comes to exhausts.
Damn, I'm old and I do love the sound of my Outlaw Bug at full song, especially with the straight pipe on sans muffler.
But... to be in Glacier National Park miles from a paved road and hear a Harley with open pipes on the Road to the Sun miles away... no love.
If the cat is more restrictive than the muffler, making it louder won't improve performance. On a naturally aspirated commuter car, it's unlikely it'll make any difference.
Best way to improve performance whilst maintaining good sound levels is to install a rotary muffler like this one:
Based on the title, I assumed you were contemplating starting a lucrative, but risky catalytic converter theft ring.
Nah, been in jail, you wouldn't like it.
The one thing that will help and is cheap and easy is to replace the intake tube with the larger one from the turbos. The NA one is ridiculously necked down to make it quiet, and the turbo one extends over the fender lip to get into ambient air, while the NA one opens into the engine bay. There was definitely a power bump, particularly at higher RPM (and not much more noise).
Purple Frog (Forum Supporter) said:Damn, I'm old and I do love the sound of my Outlaw Bug at full song, especially with the straight pipe on sans muffler.
But... to be in Glacier National Park miles from a paved road and hear a Harley with open pipes on the Road to the Sun miles away... no love.
I'm with you on that. I hate really loud vehicles - the drivers of those are selfish jerks with tiny genitalia.
In reply to 914Driver :
Lots of good info here on how to create a performance exhaust system for cheap:
https://grassrootsmotorsports.com/articles/how-build-inexpensive-quiet-exhaust-doesnt-cost-ho/
If you're talking about the 2.1 car that you bought, just pick up a stock 16V Turbo exhaust and bolt it on. Yours should have the same cat flange as a turbo car. It'll soundgood and delete one of the mufflers, all while bolting right on and being made for the chassis. I've done it on 2 or 3 N/A C900s and always enjoyed the sound. I'll likely do the same with the '92 S that I'm working on right now.
Keith - I like the 'rotary muffler'!
And they do quiet an exhaust down quite a bit although in a closed car you need additional silencing to reduce resonance.
Completely agree that wide open exhausts are annoying. I built a header and exhaust on our MGC and it sounded good but if you fired it up beside a car with a car alarm it would set it off. Had to add a tip resonator to reduce that crackle. Love the RPI rear boxes on my Z4M, though - foot out of it, pretty quiet, foot to the floor = glorious sound.
RacerBoy75 said:Purple Frog (Forum Supporter) said:Damn, I'm old and I do love the sound of my Outlaw Bug at full song, especially with the straight pipe on sans muffler.
But... to be in Glacier National Park miles from a paved road and hear a Harley with open pipes on the Road to the Sun miles away... no love.
I'm with you on that. I hate really loud vehicles - the drivers of those are selfish jerks with tiny genitalia.
Believe it or not, I do try to get my rotaries as quiet as possible 
Been spending a lot of time in my '81. I know the exhaust is pretty restrictive, but at the same time the engine note is dominated by gear whine from the stationary/rotor gear interface, which is nice and nostalgic.
But the other one... there is only so much that can be done.
Anything in here help?
How to build an inexpensive, quiet exhaust that doesn’t cost horsepower
And another vote up for "rotary muffler."
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