You have to open her up and get a picture of the centre. It might very well be welded.
If you don't want to open it up change the oil and see if it helps.
If we are talking about useable power for the street then no one should go over 300kw like anfanee said.
And let's be honest pete, your original setup was a donk from the dinosaur ages and you will forever be scorned with "ultimate lag".