Pipe/Cam combination

For the motor guys out there...What's the best muffled pipe (brand, diameter, stages) and cam combo on an adult unrestricted flathead for a big track vs. a small track and why? Thanks.
1st pipe I always test with for pretty much any modern slapper cam is the Rapp 906 x 18.. small bullring tracks I run a 906 x 20 rapp

Dovers solution is very good on most engines.

all the above are for a stocker