shouldn't affect anything to drastic man you wouldn't be flowing enough now to out flow the current system so i wouldn't worry about the extra pipe being added.
as far as noise goes should make it a fair bit louder and on a natro thst system will be WAY over the legal db reading... also if your gona be fully hella flush sickness and stick them out a foot past the rear bar copas will hate you, and expect to be pulled over alot...
tldr, won't affect anything, will be louder and illegal