I am going to be interested in hearing the answer to this. I have been told it doesnt matter, but if you look at a 5th gear run vs a 4th gear run there is a difference. I hope you get some feed back on this one. I only know enough to be dangerous but I think it would make some difference, just how much
I agree the more I think about it the hp is the hp no matter what gearing you have. As for tq I think it might just shift where you see it come in on the dyno chart. You will certainly feel a difference in the seat of the pants.
Dynos are measuring at the wheel not the crank. A gear change changes the load. It would be like pulling a nail out with a hammer, hold the hammer at the head and you have no leverage, hold it on the handle and you do. Same person / same HP just different torque.
Well, like the old saying goes...you can't race a dyno sheet. The gear change may or may not change dyno numbers. But as hotshot says, 'you will feel it in the seat of the pants'. This is why drag cars go to different gear ratios...