That graph your mate plotted doesnt have an 80 trim on the inlet trim.
So it would have more lag than the plotted graph suggests if thats the case.
Turbo is not an exact science, the expected can have totally different results.
Just go for it you can change the inlet anyway later if you need to but try it
and see how you go as suggested you never know you might like it.
Some engines on mild boost give better economy than big late boost.
A friend used a t25 from a saab on his 1300cc toyota corolla & went very well,
rpm redline stayed the same yet double the power and very responsive.
His was .48 A/R, 50 Trim, ex. .48 A/R, 60 Trim. with 1.75 su, 2.25 inch outlet.
The saab variable Jmac was talking about didnt come to Australia as far as
I have seen with the turbos if so maybe all done with variable manifolding.