Just didn't know what it takes to make sound requirements at the track. Most in my area require 103 dba; I think laguna still requires 92.

Does a turbo'ed car need a muffler; or, will a straight pipe with a turn down after the rear axle suffice? If a muffler is required, what works with a turbo'ed car?

Currently have a 2 3/4" down-pipe and 2 3/4" mid-pipe; I haven't plumbed the rear yet. ? muffler or turn-down elbow?

Thx

 

I can't speak to 103, but I do know that at Qualcomm Stadium where the AutoX crowd stops on their national tour, the limit is 93.0 dBA @ 50 ft and at least some of the turbo guys run mufflers.

 

Without a cat, you'll need a muffler. With a cat, you won't.

I drove to the exhaust shop with an open downpipe*. No way that's under 103db. I've driven a lot with just a cat, and that's doable. Trackable but barely streetable. I imagine only a muffler is the same.

Drove back too, apparently they can't touch a cat unless it's brand new.

 

You should be fine with no muffler at most tracks that don't have strict sound requirements. Savington's black car (Theseus) runs no muffler at all tracks except Laguna. Noticable difference in spool/response with no muffler vs bigass Magnaflow Laguna muffler.

This is assuming you have a turbo. With no turbo, some muffler is required.

That being said, I've begun liking to have my cars quieter. Still loud enough to hear, but not enough that your ears are ringing after a race.

 

Jesus, no muffler beyond the turbo? I must be getting old. I hit the "I want quiet" point in my life too soon.

 

Just tubing to get it to the rear.... that is for now.

 

In for pics of your "rear tubing".

 

https://www.miataturbo.net/insert-bs-here-4/tale-two-fissures-story-worlds-strangest-man-his-colon-65391/