As said earlier, screw the neighbours. What do you plan to do, sit at home and play with the throttle? Surely starting and driving off leisurely can't be to noisy!
My neibours like the sound of mine, well one does maybe the rest hate it
. Anyway I decided it wasn't noisy enough so went the full monty with sound (posted here before http://www.m3post.com/forums/showthread.php?t=315489
), I mean if you are going to spend some coin get some value out of it! (by the way mine was $3000 fitted).