i was thinking about what would happen if you drilled a hole in the sleeves, on the back side, allowing for a small amout of extra air to enter, and still have them in working condition so the can flip and be used to produce max power.
is it worth to try ...?

 

Do you mean a hole on the opposite side of the opening? I don't see how that would increase performance any. It may lower power down low and won't to anything up high.


Santiago

PS- A picture would help tons

 

it won't help... you might want to try cutting excess metal from your sleeves to help increase the area of the port, but that will net you very little.