Joe,

You are wrong about the V2 and 427 not being the same. They are the same and both have 7 ports. I can also tell you that with out a doubt the v2 is WAY faster than teh sh28. The sh is a great engine its just not on the level of the V2.

Defmeg,
The plastic cover on the air filter will restrict airflow so you will not get the full power that the engine is capable of. Get a filter with the pre filter and you will have to retune slightly and see the power increase.