There is little difference between powerflex and super pro buddy, the shore (hardness) rating of the bushes is the same, the only real difference is that the steel sleeves in the powerflex are stainless whereas the super pro are mild, but if like me you coat the bolts in axle grease there shouldn't be any issues with the bolts rusting into the sleeves, I have all of the rear suspension bushes on my car in super pro and haven't had any issues with them apart from the usual squeak when the grease dries out, but all I did was get some better stuff made by Dow Corning, so tbh mate I would go for the Super pro and as Nomad said speak to Ross at PRI racing, top bloke and always willing to help out.