Stewart, agree with above sentiments but be VERY careful with your indie, I went from indie to OPC because they were cheaper (On my 944S2)!! The indie had a lower man hour rate but my experience was they loaded the labour hours and it ended up costing me more, when you added in OPC service and coutesy car plus lower bills because of less hours and a bend over backwards attitude, and no hassle (arguing) over the bills my local OPC was best, interestingly, now with 993 ownership I have gone back to an Indie, much further away (very near the Queen in Datchet ;-)) - I live near Swindon - who is truly excellent, low hourly rate, no hour loading and a better deal than my local OPC who is still very very good - found the indie by personal recommendation. Moral, check with other owners of your marque before deciding where to go Indie or OPC it is all down to the garage. Also don't forget that your bill is made up from Hours X hourly rate (plus parts) and a low hourly rate can be more than outweighed by large number of hours, plus you don';t want too much of the standard book rate crap, which is were mechanics earn their bonus (by doing jobs quicker than the book rate yet charging book rate)
Hope above helps, you can't beat personal recommendation
John