Call me mad,
but I did this a while back I bought a Raleigh MTB it was a Y-frame in alloy just loved it but the components were crap to say the least, firstly the chainwheel buckled on the second day out and the shop would not replace it as they said I had damaged it.
The second thing the wheels would never stay true, I tried rebuilding the front one but still no good, so after month or so I started to uprate every thing XT hubs on Marvic rims, full XT chainset, and brakes, carbon seatpost and handlebars next the suspension Pace front forks and Strata rear.
I love the bike now it rides like a bike should be very smooth OK it is still a Raleigh and always will be, but I love ir even if it did cost an arm and a leg