kung_powpowDude whatever you do, don't do this. This is wrong in so many ways and will end up with you and your bike being broken. If your bike miraculously doesn't break, then you'll want to break it yourself after riding all that fucked up geometry.
Also, there are more consequences to this then you would think. Geometry affects the riding characteristics of the ENTIRE bike.
-First off, warranty will be voided
-Added stress on HT through the back of it, rather than up it
-Slacked seat tube
-Higher standover height
-Higher BB will result in reduced cornering grip, and weight further back
-Worse performance on climbs, flats, technical sections, and slow speeds since it steers slower and has a higher bar height
The only good thing out of this would be your bike will handle much better on fast, straight descents.
OK, not to get in an argument but let me just address your points here.
-True, but only if you are an idiot and take it to the shop saying "I put pike on it and this happened"
-Unless you're a total hack, that bike won't break at the head tube.
-seat tube is plenty steep on a camber, 1 degree slacker (w/ 150mm pike) is nothing. besides, no one cares about their seat tube angle anyways. slide your seat a little forward.
-standover varies by almost a foot between bikes. it's pointless unless you have midget legs
-OK, this one is legit. won't corner quite as well. but again, BB (w/ 150) is raised by about 15mm, which won't make a huge difference unless you can actually corner well.
-Duh, but I'd assume he's aware of what comes with a bigger fork/slacker bike.
I'll reiterate that it's not a good idea in the first place, but if you want to drastically change your bike to ride much more aggressively on a budget that can only afford a fork, then buy the fork. fun is fun