thats a big question mate. cant really answer the whole thing! the swap is pretty much straight forward. only the wiring that needs sorting (to fit the turbo ecu). everything else literally bolts into place. any specific questions though, and ill give more detailed questions.
youll have to get them test fitted and gapped first mate. fit the cams to a head and have someone look. if they are billet ones they should have the the lift the same as stock mate. chances are your shims no should be ok. but like i said, test fit.
its dooable with the mani on, but as paul said, its HELLA easier to just take it all off. youll turn the air blue trying to get the rear manifold bolts off.
if you get newuprated cams (ie, regrinds) then youll need new shims made. that you wont get at toyota. average price for a reshimming is about 200-250 quid.
what cylinders is it running on? the injectors cycle in pairs. so it could be that. 1-4 2-3 id recomend a compression check though, you could have blown through to the next cylinder on the HG.
just fitted it and found out its the same as the 4e. it must be the little plate on the pump thats different.... ;) you got an exploded diagram of the pump itself? its a goldy coloured plate that bolts onto the side. also, that belt you sent was too wide bud. it wont go on the pulley? any ideas?
the piece you sent mate wasnt the right one ;) it looks like you sent me 33534C. the piece i need is the 33548F. its like a little white plastic cup looking thing.
cod is also becoming loss. too many kids playing it. BFBC comes out soon, so ill wait for that bad boy to resume my multiplayer passions. GTA4 is fun on multiplayer. but hardly anything serious or challenging.