I was wondering for those in the know, as to why or how prince gets his symbol guitar to have a real scream tone when playing solos.

Notiablly in his "The Ride" performance on the Vagas DVD, I love the tone he is able to extract from it.

Is the locking tremlo, pick ups ect or just his technique.

Thanks in advance!

A combination, I suppose. It sounds like he's using his Boss Turbo Distortion (lots of mids, not so much sustain) on it. But IIRC he runs through numerous effects in this tune.