Questions regarding Aftermarket standalones
 

Hello,
I am planning to upgrade my stock ECU with a Wolf EMS sometime soon,
however i can't help but notice the V3s are selling much cheaper than the V4s.
how different are they and is it worth that much to buy the V4?

and just a general question since i heard this in sevenstock
can you really tune the ECU good enough that on cruise it can run 25+ mpgs?
also make it pass smog easily?

thanks

Jonathan