The RB 928 doesn't have the best tourque, it is more of a Truggy engine with more emphasis on midrange and top end as well as fuel economy.. they are also very tricky to tune... In a heavy vehicle like a Savage my money would be on the modded STS 30 ( basing off my own modded STS 30's) ......... the Nova 28 is a different animal altogether, it has insane bottom end tourque and a very broad powerband, not as much top end as a 928, but its bigger power down low will likely make for a faster MT motor, it is also a pig on fuel and was designed as a MT motor..... Another beast of an engine is a Picco 28, which again in a MT i would take over a RB 928 due to the Picco's massive tourque, it makes a true 2 HP on the X-Dyno and has a screaming top end, and as well the Picco 28 is a very good platform for mods....The STS 30 is the cheapest and will obviously lack the durability and longevity of the other motors, as well it is tricky to tune, but it does have an insane bottom end and midrange and a very solid top end.....in a heavy MT you want tourque, and the Nova 28, Picco 28, STS 30 have awesome tourque, with the Nova and Picco having the strongest off idle snap.. the RB is going to have less tourque, but make up with a screaming midrange and top end......