This stuff is exhausting...

[JohnW8]

I'm driving a former spec miata in ITA and am looking to make improvements to the exhaust. I've added a racing beat header, which isn't ideal but it was sitting on the shelf in the garage. The car has the Springfield Dyno exhaust which is very popular in the Spec Miata class but it's dang loud and lacking in low end torque. What would be a good source for info regarding a better exhaust system for a Miata that helps low end torque, still breathes up top and quiets things down a bit to eliminate sound violation worry at some tracks?

Keep in mind, I'm not made of money.