Dont get a S13/S14/S15 LSD if you planning on any drifting, they suck as bad as Cossie and RST ones.

Regarding plugs, use Saab 9000 turbo ones, they same as S13 ones but 1 heat range colder, good for over 300bhp and about 20quid from halfords

Get the S13 NGK part number, think it ends in a 6, and get the same number but 1 grade up, making it a 7, possibly and 8, i forget, deffo not a 9/10/11 as they badass racing/rotory plugs.