You shouldn't need 4" spacers for the bump stops. I only had to cut the rear of the front and rear guards (so called Camel cut) and modify the rear section of the rear inner guard (above mud flap) with 33" tyres.
With 4" spacers under bump stops, unless you lower the upper shockie mounts, your shockies will only have an effective 4" travel (stock shockies have 8" stroke) - bit more for rears because of their angle.
With stock bump stops, shockies and shockie mounts, 3.5" suspension lift reduces your droop (down) travel by 3.5", but increases bump (up) travel by 3.5".
With 4" lower bump stops, 3.5" lift and stock shockies, bump travel is 0.5" less and droop travel is 3.5" less than stock.:eek:
I have about 3" spring lift and 10" stroke shockies. My springs are softer than a lot of others, but I like how well they go in the rough stuff. I still hit my bump stops occasionally with 3" extra bump travel - I would hate to go back to 0.5" less than stock bump travel.
Edit: BTW, you have a Discovery, not a Series 1 - big difference. ;)

