16/45 would give you a 2.81 ratio; very close to the 2.82 you would get from 17/48. I got the gear ratios from
this site.
I think I read that it can be dangerous to use smaller front sprockets with the T3 motors due to tight clearances, but I can't remember details. I see that JT Sprockets doesn't make anything smaller than 17.
Maybe I'm missing something, but I don't understand why your bike is stalling or how changing sprockets will prevent it from doing so.
Just for reference, my Trident has the 97 HP 6-speed engine, 9700 RPM redline, 18" rear wheel, & stock 17/46 gearing. 7500 RPM in 4th is about 80MPH for me. (I think; I'll update next time I have a chance to verify.)
HTH,
-Kit
