Given the 95dB limit at the new Atlanta Motorsports Park, what are our options? I was right at that limit at the TGPR TT (no limit, but they were checking to give people a heads up for AMP). I remember an expensive and complicated Spec muffler, but I can't find it in a quick search of a couple CSRs online part catalogs. Did it or the requirement to use it go away? Can we add a simple turn out pipe and clock it away from the meter?

I have a simple pipe end Supertrapp that I use for Solo. $30 part and I can put it on or take it off in 5 minutes. I assume this is not legal for Road Racing (Solo sups typically have something about mods allowed to meet sound limits, which is why it is legal there).

BFun wrote:Given the 95dB limit at the new Atlanta Motorsports Park, what are our options? I was right at that limit at the TGPR TT (no limit, but they were checking to give people a heads up for AMP). I remember an expensive and complicated Spec muffler, but I can't find it in a quick search of a couple CSRs online part catalogs. Did it or the requirement to use it go away? Can we add a simple turn out pipe and clock it away from the meter?

I have a simple pipe end Supertrapp that I use for Solo. $30 part and I can put it on or take it off in 5 minutes. I assume this is not legal for Road Racing (Solo sups typically have something about mods allowed to meet sound limits, which is why it is legal there).

Talk to the Laguna Seca folks. There is a spec muffler because of the very low levels they are allowed out there.

Enterprises sells a muffler (the same one as the FE car) which will meet the 95 dB limit. At Laguna this muffler was measured at 92 dB which doesn't meet the early morning 90 dB limit. The CSRs sell a turbo muffler kit (downpipe, muffler, and mounting brackets) which will meet the 90 dB limit. If you have never driven a SRF with a muffler be prepared for a whole new experience as you can hear every squeak and rattle.

Unless it is a different muffler than the one we call the "Portland" muffler (because you have to have a muffler at Portland, but it doesn't have to reduce the sound ), the "new" muffler doesn't reduce sound much more than a db.

dave wrote:Unless it is a different muffler than the one we call the "Portland" muffler (because you have to have a muffler at Portland, but it doesn't have to reduce the sound ), the "new" muffler doesn't reduce sound much more than a db.

The "Portland" muffler is the one Bob Gardner mentoned. Same one as used on the FE.
It will typically run about 95-98db. Be very marginal to make 95db consistently depending on conditions. The quiet mufler is as described above. Easily meets < 90 db (seems like tire noise exceeds that!!!!!). Also serves as a nice bumper in the rear of your car to protect the nose of the guy bump drafting you.

PS Dave is correct....our straight pipes will easily clear 103db sound (and City and State limits are 105db) but State of Oregon requires a "muffler" of some kind, thus the use of the FE muffler up here.

PSS the FE muffler does sound better than the straight pipe tractor motor sound.

Todd SRF73 wrote: Dave is correct....our straight pipes will easily clear 103db sound (and City and State limits are 105db) but State of Oregon requires a "muffler" of some kind, thus the use of the FE muffler up here.

A car should make 101 with a straight pipe.

Todd SRF73 wrote: PSS the FE muffler does sound better than the straight pipe tractor motor sound.

Sort of a cross between a tractor, a F500 and an RX-7.

Don't these things cost ~$500 for the full setup?

I hate to spend an extra $500 for a single race (or even one annually). I assume the standard trick of adding a turn out pipe pointed away from the meter would be illegal as a modification of the spec exhaust? I was in the 94-96 range at TGPR so I just need a little help to meet 95.

Anyone test the quiet muffler to see how much HP it costs? If I did get one, I might be tempted to just leave it on all the time and stop wearing ear plugs.

A quick lift when passing by the meter costs less than $500 as well.

As if Denny ever lifts!

Racer X wrote:A quick lift when passing by the meter costs less than $500 as well.

I ran Atlanta Motorsports Park yesterday in a loud Honda S2000. They limited us to 98dbA and we were measured at 99. So, we put a resonator insert in the tailpipe to get us under the limit.

The track staff told us in the morning meeting that the db scale they use is the A scale, different from some of the other tracks. Also, they measure at various places around the track so lifting would be futile. I'm not sure, but I think our cars may come close to meeting the limit without a muffler. Maybe Jean Luc could tell us if he still has his Spec Racer???