Alright guys I figured I would pose this question to you guys since I got into it with a guy over this on another site. Okay so this guy has a vitara and eagle built z6 block with a minorly home ported z6 head, turbo motor. He was pushing around 300 horsepower on 19 lbs of boost, on 550 cc injectors. I asked him what intake manifold (to which he replied y7 manifold, he had been running a y7 head until he bought a z6 head to add a little more power)he was running and mentioned a quick cheap way to wake a couple more horses would be to run to a junkyard and get a throttlebody off of a b, h, or f series motor since they will bolt onto a d-series manifold and are 60 mm rather than 55 mm. This other guy began to argue that with a properly ported manifold and throttlebody would make a 20+ horsepower gain. I responded telling him that I wasn't saying anything about the manifold and that I didn't doubt it that getting a z6 or y8 manifold and porting it properly with a bigger throttle body that he would make a 20+ horse gain but I was simply talking about how just throwing a junkyard throttle body on his setup wouldn't be a huge power gain on the stock manifold he has on the motor. So does anyone who knows a bit about the flow dynamics of a motor know about how many horsepower can be had from simply taking a throttle body from a b, h, or f-series motor and putting it on his setup? Keep in mind I am not looking for a specific number just a ball park estimate with a quick explanation as to why he would gain that. I am not asking to argue anymore but hell if I gain anywhere over 5 horsepower I will throw my f22 throttle body on my motor.