You've obviously never taken your bella to the limit on bends then
Nitrous is far more complex than people think, early systems could easily overfuel which would hole your pistons less than a second, the latest multipoint injection systems use a separate ecu much like lpg sequential injection which is very expensive and can be a pig to set up.
Not that that is bad enough but a bottle of nitrous does not last long period.
I am also in the custom bike scene and know guys with nitrous on there bikes, they will tell you first hand it is for the drag strip only and if your gonna spend thousands on strengthening your engine.
Turbocharging a ts would not only involve fabricating your own inlet/exhaust manifolds, picking the correct size turbo, reducing your compression ratio to suit boost pressure, increasing cooling system capacity, prob adding an intercooler, custom ecu fuel map, all for what? Have you got a huge disposable income?
If you have then buy a v6, there is no compromise for power, torque and reliability than adding more cubic capacity.
If you just want a few extra bhp then either have a chip fitted to your ecu or if its a later ts have it remapped.