I've considered all the variations--toggling from gas to lp would be ok, but require a lot of modifications--and some place to put an extra, large tank. With the simultaneous system, you only use a 2.5 to 7 gallon tank, and the kit doesn't look like a multiple day job.

Also, 'cause the guy also says it will improve mpg by around 25% while increasing low-end torque--again, two things sorely lacking in the rx7.