You lose a tiny bit of bottom end, nothing worth noting. I want to run a full exhaust, but I'm spending my money elsewhere currently. Removing that little valve has hurt nothing. I have 13,500mi on my 07 and that valve has been more often than not stuck close. So I'd rather lose a little bottom end, then have it staying closed at interstate speeds and bog down at 8,000 rpm if I try to punch it. It was a valued trade off.by doing that its like if you put a new exhaust on it as they dont have it either but you still have that huge cat. By doing what you did you are gaining no power and actually losing some at lower rpm's. When removing exup with full exhaust you get power because you are losing weight and opening up the exhaust , might want to look into getting full exhaust now. on stock exhaust leave the ex-up on as it does work better on the stock exhaust.
just my two cents not the guy who designed it but definetly done alot of mods myself.