2V vs 4V pre-amps

I am giving my friend my Soundstream amp. He intends to buy a head-unit with only 2V pre-amp outputs where I had 4V. Will this make a significant difference to him? should he spend the extra $20 or $30 for the 4V outs?

it only makes a difference if 1) the low output allows engine noise 2) the low output means you have to turn the amp gains up so high you get hissing in the tweeters.