Road bike for the road.

First off you SL5 is most like 17-18lbs and a MTB would be in the mid to high 20s.

If your bike is stock I would assume it has a 50/39 compact crank and a 11-28 rear. I would change the inner chainring to a 34T and put a 11-32 on the rear. The 32 rear should fit with the stock RD.