Mate i dont trust any of them. Exhaust shops and even tyre shops. Got a wheel allignment once.(obviously cant do at home) and guess what they broke the linkages in more door. Pulled it apart to find considerable forsce had been used becasue they tried to open it without first unlocking it. Duh.

I do absolutely everything myelf or with a little help from family members. I must admit though dad and my uncle are/were qualified mechanics and have taught me alot. There is only so much they can help you with though. The rest i learnt just by stuffing around and doing it without asking. Sure a 15min job may take an hour but i know how to do it next time.