I have a miltek fitted at the mo, and its louder than the cobra 3" trackday friendly system I had fitted previously on full chat, but quieter on idle/static testing! I think a cobra with their standard sized trackday friendly system in 3" would be ideal, I think it flows a little better than the miltek too after back to back testing.
For comparison Sam check my Doningtion vid with Tim in the passenger seat (2 laps or something before black flag with miltek), next to Goodwood clip with passengers.. bare in mind that I asked for a custom 4.5" exit on the cobra which would have increased the volume a lot, but you will get the idea
Lucky break with the cambelt, I saw a high millage wrx up at Rich's a few months back where they had not been so lucky and the belt had wrapped round the crank pulley and locked it, all the cams jumped and it was bye bye engine! compression tested all cylinders... 0 !