98 328i 5 speed rebuild

I have an E36 328i that has many problems, but two very important problems are the clutch and 5 speed. The 5 speed gives me some resistance when I row through the gears and I had my co-worker drive it. He just had his Mazda 6 5 speed trans rebuilt and he said mine needs to be rebuilt. Since my clutch just started slipping, now is a good time to get info before I yank both out.

So, do I just need to get a rebuild kit from BMW or do other companies have them too? I also will probably do a little autocrossing with it so making the trans handle maybe 10-20% more torque would be a good idea.

Thanks.