A good cheap way to have a tighter diff is retain the stock LSD, but 'shim' it up. By adding extra preload shims (which are around $10 each), the diff will be a lot tighter.
From factory you are supposed to have two 0.80mm shims inside the diff centre. So that's a total of 1.60mm of preload.
You can use this guide here to show exactly how to shim your diff.
http://www.skylinesaustralia.com/forums/Di...l=shimming+diff
There's a lot of discussion on what shims should be used, I ended up buying the shims from my local Nissan dealer. I ended up having 2.45mm of preload. It skipped the inside wheel pretty bad for about a week and then it loosened up just a tad. Still feels very firm is very predictable when driving or drifting.
Just have a read of that tutorial link and it may give you some ideas.
-Jimmy.