best fing 2 do mate is go on www.demon-tweeks.co.uk

there road legal ones are about £800+

and they can do fings like, speed, rpm, boost pressure, oil pressure, fuel pressure, water & oil temp, battery, fuel level, air temp shit loadz mate u get the idea..

they do look the spec but my mate who works for tweeksies says he wouldnt have one in a road car for the hassle of the wiring and the speedo can sometime be a bit over zelous, and that they do tend to break easily with alot of use youd say in a day to day car.

what he says tho so dunno how true, mind he is a racing driver n works there so..