Joskin is right, you can get through absolutely loads of groundbait and at ?3-4 per 1 Kg bag in the shops it could cost you ?12-15 for groundbait alone when fishing a session. Therefore, I buy mine from the local farm shop - ground pellet is ?20 for 25Kg, brown crumb is ?11 for 20Kg and crushed hemp is ?16.50 for 20Kg.
I use a mix of 50% ground pellet, 25% brown crumb and 25% crushed hemp. Sometimes I'll put a few floating pellets or such like in the mix.
You could also try adding some vitalin after breaking it down a bit in a food processor.
I want the mix to break up fairly quickly as I'll be casting every 90 seconds or so. Once you get the fish interested the bites are almost immediate and the carp generally hook themselves. I warn you to hold onto the rod as it'll be in danger of being dragged in if you don't do so.
I've not heard of using the powergum link for this methed and I can't see what benefits it would have - you're using fairly heavy tackle for hard fighting fish. The rod, line, hooklength and hook should be sufficiently strong enough to handle the bagging waggler and the fish without the need for a "shock absorber" built into it - the natural stretch in the monofilament line should be sufficient.