B4 advice

[mpg200]

I'm about to have another go at 2WD, Ive got a B4 and planning on using a 10.5T motor running indoors. Now in the past I have used a 20T brushed in it and had some quite pleasent race evenings at york when I found it rewarding do drive. But the last time I drove it, it was a nasty hateful endswappy beast with not respect for who has the controller, and we fell out big time. So, what is a recommended setup for indoors so me and my B4 can be friends again, also how tight should the diff be? I dug it out last night and found it to be very tight, surely this cant help?

Thanks

Matt