Hello monkeywrench and welcome to the site. Where are you from? Fill out your profile so we know abit about yourself.

Your question about changing the pinion angle is a good one, my answer is I have been adjusting the pinion angle (via the adjustable top and bottom four links I have made up) over the last couple of rallies I have been in. The changes I have made to this area have been by far the most significant changes I have made to the rally car with respect to getting power to the ground.

Prior to the changes the pinion angle was at 4 deg positve, I thought the car handled pretty good with that. After fitting the adjustable link arms and setting the pinion angle to 1 1/2 deg neg. I was completly amazed at the difference to the whole car it has made, it really is truly amazing.
No axle tramping off the line, the hook up is instant, before I would have to wait till after the apex of the corner before I booted it now I can literally attack corners before entering them knowing full well the arse end is going to stick to the road. This modification alone has given me nearly two seconds per Km and best of all it has given me more confidence in the cars handling.

So as far as I'm concerned if making the gearbox and the pinion angles is a lot of work but if it give me a chance of getting more power to the ground its very well worth the effort.