Very well put. Here's a little something I found on the back of an Import Tuner mag as far as exhausts are concerned...
These results are for a Subaru WRX but you should get the idea. dB = decibels. Sorry Tsudo wasn't on the list.
Code:
dB@idle dB@3000 Peak HP
Stock 87 86 191.8
GReddy 94 92 200.9
M2 94 94 195.9
Super Sprint 95 101 198.0
MRT Perf. 96 104 198.0
HKS 97 102 202.9
Cobb Tuning 97 103 200.0
5Zigen 98 105 198.7
Apexi 100 104 201.1
Tanabe 101 107 197.7
Thermal 101 108 198.3
Skunk2 102 106 199.3
Blitz 104 103 200.2