Honestly... just speculating... I havent dove this deep into my own l67... but from what Ive read and seen, your bottlenecking the motor. the Gen5 has alot of potential but your not reaching it, and I can understand you wanting to go to the TVS because it is more efficient, but I honestly don't think you will turn any better number by just swapping the blower unless you do some updates on the little things.
Like the injectors. More air, better flow, fuel to compensate... you don't get enough fuel you will run lean and .... we all know where that leads. Get the blower but don't forget the basics