Whats the lowest ground clearance between the sump and the groung you can have as ive only got 3 inch clearence do you think tis is enough?

Not for road use --- aim for 4 inch / 100mm minimum
Watch particularly the clearance under the bellhousing.

[Edited on 10/4/04 by britishtrident]

Can't you adjust your ride height?

If not and you do decide to use such a low clearance, I would suggest you fit a skid pan.
This will deflect any obstructions saving your sump/engine from terminal damage.

Very easy to make and fit.

Tigger

Have you done a sump chop?, the bottom of my chassis is 5" above the ground and my chopped sump is 1" below the chassis