In an '01, the first thing I would recommend is egaging the center locking diff. It's still there, just not engaged. Find a reputable indie Rover shop in you area to do this. Next I would put the OME suspension on (money warning: 4-wheel often w/ this suspension & you may end up wanting more lift/drop down the road
). With this, of course, you'll want to upgrade you tires so you that you'll have what you need where the rubber meets the trail. Long debate about tires,,, but pretty much depends on where you live (or where you wheel, ie: the terrain) and how much you will go off-road. I am a big fan of BFG A/Ts but everyone has their favorite. You can probably get along w/out the bumpers for awhile depending on how much you go off-road. You can turn your stock bumper into a "Kalahari" style bumper fairly easily. And don't forget rock sliders---very important and practical piece of equipment and they provide you a solid Hi-Lift jacking point.
It's best to pre-plan what you want to do, as you'll save money over the long run. Example---if you get medium OME springs you'll have to upgrade to heavy if you put on a front bumper. Again,, if you are seriously interested in taking your Rover off road,,,plan it. If I could go back & plan my build-up differently, I would have saved a ton of money.
Check out some reputable sellers of aftermarket mods: www.rovertym.com
,, expedition exchange,,many others out there. Atlantic British tends to be on the expensive side and are more for stock replacement than true off-road mods.
Finally---stay tuned to this forum. Try some searches and look at past threads in the Discovery & Off-Road sections. Many opinions, lots of good advice. :drink1: