welcome to sau
as you already said, the police are just doing their job, if you have an illegally modified car, expect to get harrassed. personally, i've never had a positive experience with the police, even the times when i needed their help with stuff.
what rights are we going to stand up for, the right to break the law? (however stupid the laws may be)
if you're friend is finding it hard to pass the EPA test, then he should either return it to stock, or liase with a tuner who has experience with passing emissions test eg. hitman injection tuning in penrith
your football analogy doesn't make any sense, and do you really have an r35 gtr lol?