It's all about competition I think.
If the guy in the next lane up the ante and 'goes blown', you either have to pony up your motor or follow suit.
I also think it's a "natural" process of increasing the power in a car. It's either building a stroker or pressurize the intake.
On a personal note, eventhough I don't have competition to deal with, I still want to have a blown motor... Just for kicks, as I don't have the ability over here to dragrace on a regular basis.
So I'll just build the motor to beat the neighbor to the local supermarket maybe... Artificial competition?
