I had another quick email exchange with Matt, I explained I am after higher revs torque and his reply was (based on the requirements I sent him):
"the TW 21 is designed forheavy bikes and is designed to increase torque in the lower rpm ranges,not what you have described to me as your needs,I would recommend the S&S 510 or 570,or the andrews tw37b,rough idea of cost for cam & pushrod change,headwork & dyno tuning would be likely to be around £1300,"
So £1300, does not sound that bad. I've replied to say I'll contact him Sept/Oct time to book the bike in and get it sorted. Might change my handlebars from apes though .. not great at high speeds with high headwind ...
