1. To alter the drive belt tension you have to move the rear wheel, there should be a set of instructions on how this is done in the handbook. Alignment of the wheel and the drive belt is critical to getting it to all run correctly. 20 deg is tight, about 45 - 60 is about right. If your car has the NVH kit fitted the belt should be on the tighter side or it may jump teeth, non NVH can run a bit slacker.
2. Try contacting "Bunny" about the rear sprocket, he has had one done recently and has all the information. He may have a spare sprocket as he had my old one to send off.
3. Has your oil tank got two tabs inside at different levels when you look in through the filler? If it has these are the high and low levels. Check the level a few minutes after running.
You have been busy with the mods, all good stuff. The G56 system is expensive but very good and worth it.
