I lowered mine myself last year. I'd never done anything like that before, but by following the article on brickwerks (and ringing garrick up when I got stuck
) I managed to do it myself. It makes a huge difference to the handling
The backs are easy - you don't even have to take the wheel off. The only hard thing about the front is getting the springs in/out - it's really tight. I had crappy spring compressors, but I'm sure if you had a good quality pair it would be much easier
You only need to cut the bumpstops down if you're keeping the standard shocks on. The Avo shocks that I got came with replacement polyeurethane thingys, so the standard bumpstops aren't needed at all. You should also get your camber reset after lowering it.....although I haven't yet