Tropher Tony, 90* are a bad idea and more in a multi loop ie: CPU, NB, GPU etc etc.

However, 90* in the form of Beer line cooler, copper fittings are fine as they have really big bores and are made for high flow!

DD, Nylon 90* are what make the flow low. Big topic showing this in WC here!

Baz its fine, i'd of told ya if not