The thing is though, I have HFC xpipe with OEM rear and it sounds exactly like the Innotech F1 rear. So if you are willing to do a high flow cat xpipe for 2300 bucks from AA than you can have that same sound PLUS 20 extra hp. So really its a ton of money for a sound you can easily get from HFC.
It is impressive how they get that sound when nobody else can from a rear. All other systems cannot get there without a high flow cat/catless.
Catless/HFC plus innotech would likely sound garbage as both make the sound high pitched and raspy, which is great but too much may be just not a nice sound.
If you like the sound and dont really need the valve, go with HFC. 20 hp plus the high pitched f1 sound is the bargain of the century. Catless sounds identical to the BMW m3 DTM race car only a few notches quieter but same sound quality