Sorry for the stupid question but I take it you trim from the rear taper rather than the front taper?
Matt,
I worked out that I wanted about 15g at 26' to use with 7' polyleaders. I chopped off about 40' of DT 10 and cut bits of front & rear until i got the length / weight right. I chopped back the front until it felt slightly thicker than the thickest polyleader I would be throwing, the intermediate. My head turns quite hard, I would not remove all of the front taper although if using 10' tips as Michale is then it may be o.k. removed a few inches at a time and cast it until it feels right.
Unlucky Michael, I'm out tomorrow, will see what turns up
Cheers
Ben