It really depends on how u tune and maintain your engines.I have had many vspecs and they all lasted a very long time averaging 8 gallons on stock engines and 11 gallons on my jp mod vspec.
Kforce is correct the new speed motors are fantastic and seem to last forever,not forgetting the awesome mileage and power.
You can never doubt a novarossi engine they are fantastic motors, although can be slightly difficult to tune sometimes,are pretty reliable and very powerful.
its a tough call between those 2 motors but i would say get the OS extremely quick and in my experience very durable and reliable.
hope i helped you with your decision
