alfa 156 supercharger or bi-turbo?

Ok everyone I was trying a cheapish option to give more power to my 2.5 v6 but I am just going to go all out. I want a European car for the drags so focusing on power. I want to fit in the 3.8 engine blocks and also a throttle body kit by AH Motorsports. after this I either want to put a bi-turbo (maybe novitec?) in or a supercharger kit by Z-Engineering what you all recommend? i am also planning on running nos through only pushing about an extra 50 hp through. (also ecu computer controlled chip so I can sort all the changes). I realise this is very very expensive and the engine will need a lot of sorting out aswell as trying to get traction on a fwd after this. Super slick tyres and what else? I am not rich and will take me a seriously long time of savings but I am realy dedicated to make a serious machine and I have an engine mechanic that certs and builds drag cars and will arrange it all for cheap (a little help!).
Please give me any suggestions you can to help me in any way either handling or more power. cheers

Moved to Tuning Lounge

As a long term reliable option you could consider swapping the 2.5 for a 3.2 V6. Its a fairly straightforward swop apparently.

i think it will be very difficult to fit the throttle bodys then turbo/supercharge it... normally you would do one or the other

as said, look into getting a 3.2 lump in first, will be easier than prepping the 2.5 for such use and will most likely last a lot longer too

What kind of horsepower you looking at with 3.8 twin turbos and nos.........maybe 550-600hp

ok then what you recon throttle body super or turbos? what would be more reliable? what sort of hp gain would i be looking at with the throttle bodies the problem with 3.2 is it will be a bit more difficult to source as not to many engines in n z. how about a 3.0 l dropping everything into that one?