You should listen to both Belanger and B&B. I have Belangers on my 06 SRTC, B & B's on my 01 GTS and on my 04 SRT-10 (535 CI Paxton) They definitely sound different. Muffler treatments will also affect sound as will the crossovers (with or without).
HP / TQ numbers are about the same and seem to depend more on what you have after the headers than the headers themselves.
Both are good products.
Dan