.90/4S in a CG Tiger 2? To heavy mate.
Even with a standard.46 2 stroke, that plane needs/deserves tail weight to bring it out and show just what a lovely flying plane it is.
Having said that and flown a T2 for many many years albeit, years ago, it would benefit from a little extra power, todays modern light weight .50 plus somethings for example... but a .90 4 banger is counter productive IMO. Ground clearance, extra right thrust, tail weight, tank size ... yuk.
Still, who give a F'? Just go for it and have fun.