well i garente if you pull the whole added system then it will be back to normal.LOL the weight and still draw on the alternator will still hurt your milage, it might not be as bad as 2 12s but still noticable

 

do they really weigh that much to make a difference?

 

to the butt dyno... no probably not noticeable.

IMO its well worth the cons to have my bass! im going bigger for sure eventually. im thinking another 15inch type R. and my same amplifier will work great with the extra sub since im only using 1/3rd of its potential right now.