I installed an Artec Hotrail pickup in the bridge position of my friend's Mexican Standard Strat today. He was looking to get a warmer and fatter tone than that of the stock bridge pickup.
Something I have wanted to do for quite a long time is to build my own guitar, ultimately I'd love to actually make the neck and body from scratch, but maybe that'll be possible another time.
The cheap pickups (they cost £15) that I ordered weeks ago finally arrived and I installed them in the newly refinished "Electric" Strat. Originally a black Squier Vintage Modified 70s Strat, it is now an electric blue, late 60s/70s-inpired Strat.