Exhaust cans

[CatalinU]

So the bike has turned up this morning and seems to be in great condition, just some very slight scratches on the (standard) silencer. 
Any views/experiences on good/bad/ugly aftermarket cans?  Budget £200 or less really, looking for good torque, and I imagine I'll do a 'carb jetting job' of some sort this Winter.
I've looked at PipeWerx, Beowulf, Black Widow, Delkevic, Fuel, Scorpion (bit pricey), etc.
But how to choose...?

Delkevic have some top products and also researched products. So before putting them out, they are tested