I need to make some mufflers for my 2 rental cars for the local country club track... from experience the "high-flow" glasspack mufflers often don't do much for sound and are just expensive. Any of you west coast folks have some tips on mufflers to get the cars quieter? These things are at 84 at the property line for the track, their limit is 85... would like to get them down to high-70s or low 80s at roughly 75 yards.

Power loss isn't a huge concern as these will be the only 2 out there (and I'll bolt the straight pipe on for races), but would be nice to be able to keep them as the fastest cars at the track on a given weekend with a reasonably skilled driver.

I think the turbo-style mufflers we use out here would work real well. They consist of an "L" tube down from the y-pipe (which I believe is an Enterprises part), a pretty generic turbo muffler and a stinger. We can make 90 dB pretty easily at SCCA standards, which I believe is 50 feet from the edge of the track.
I feel like they kind of smooth out the bottom end power, and prefer hearing the tires to the exhaust, so I like them. They also make good bumpers, as long as they don't get smashed.

I'll try to take a picture tomorrow.
Dave H.

Then there's always the "Portland Muffler" which meets the Portlandia standards of looking very elegant but being very ineffective at deadening sound (-2 dB?).

Thanks for the info, Dave. Any chance you've got a part number or model on the muffler?

I may just take this downpipe to the local muffler shop and see what they've got on the shelf to fit it. I was able to run one of the cars to a 1:30.8 on cycled out tires and a dirty track... the record there for a production car is mid-1:20s with only Formula BMWs and the like getting into 1:17 territory. I don't think a "street" muffler would do much harm to the performance of these things overall, and as long as they're still closely matched that's all I care about.