Just got back from a long weekend in champery. portes du soliel. Took a 5 inch travel bike. I was able to get down everything at spee , without looking like I was way out of my depth, even the really full on trails like the world cup downhills. However despite not being a brake dragger (well not all the time) i cooked my 160mm Mono m4's. Sintered pads didn't help. so definately bigger rotors if your bike will take them. Also get the biggest tyres you can. Minimum 2.35 high rollers. 2.5 on the front if you can. Also I can't believe noone has told you to fit a short stem 50mm is best 70 max. It will really help on the super steep slopes and quick bends.

On the last day i hired a commencal mini downhill 160 mm it ruled! The increase in speed was incredible, same trails just faster. It wasn't the travel it was the geometry. Geometry is more important than travel. The slacker head angle really made a difference. It only cost me £50 to hire a top of the line bike. cheaper than multiple upgrades that you won't need in the uk.