ok for a turbo heres the basics you'd need
Boost Controller
Large enough turbo
Turbo manifold for a V6
Vaccume lines
Blow off valve
reinforced intake pipe
done pipe to the exhust
2-3 BAR map sensor
sump oil return
Boost gauge so you dont accidently run too much boost for the engine
you'd want to install a oil cooler if you dont have one already because as you can imagine when a turbo spools up it can cause alot of heat.. the s2 calais came with oil coolers
Also intercooler
and intercooler piping
and maybe a external wastegate for a bit more power
other things you'd want to start considering later are
new valve springs
new valve seats (pending on the km of the car)
Reinforced headgaskets (something like those tripple layered steel ones, with new headbolts)
over all if your going to DIY you'll need these tools
a pipe bender
a mig welder
soldier iron
socket set (duh)
Angle grinder
im not a expert on the VT engine, were the heads alloy??????????
i wouldnt push the boost levels over 10psi without a intercooler and some serious investigation into your engine
if your going for massive power rebuild the top end first then the bottom end, ie heads, pushrods first then pistons, conrods,
remember with a turbo setup not all N/A power mods will have a positive effect.. some may have a adverse effect, such as a cam shaft
so do your research wisely on what parts would be best for forced induction but good luck
i believe the turbo manifold will be the hardest part,
this wont be a easy project but if you do it correctly you can get some MASSIVE gains
check out
www.homemadeturbo.com
this will give you a better idea.. just some advice.. read this post first not to piss people off
http://www.homemadeturbo.com/forum/index.php?topic=28135.0
it CAN be done for under $1000 but thats STRICTLY DIY
about $4000 for a off the shelf kit
then the most important part.... TUNING
the Eaton M90 was the supercharger fitted to the Super6s
you can pick a reco'd/new m90 up for $500-2000
then you just need a modified adaptor plate, and a supercharged tune
the stock ones come with a 6psi pulley i believe
still... a turbo has more potential because its not limited to how much boost the pulley can create... but a supercharger has no spool time
if you still are intrested in a turbo kit contact
www.6boost.com
he makes custom manifolds mainly for VL turbo's but you might get lucky and get a custom manifold for a good price
you'd need probbly a T3/T4 AR.60/.80 anything smaller than that would be undersized... good luck