The Thruxton needles have a more radical taper than the TBS which are more radical than stock. They are all not that different, just a slightly steeper taper than the lesser. Hey Pat, do you still have that pic we took in GA of the three needles side by side?
You found her stronger with a shim, right? Well, what you did was put less of the needle into the jet by lifting it which opened the jet more (don't mean to lecture but others may read this...). Don't forget, these are metering needles. Adding a more radical taper (or more shims) will introduce more power (and gas) up to (and possibly past) a point where all you are doing is wasting gas and not getting any more power. What's that point? Only your seat of the pants dyno or a real dyno will tell. I believe it was SalMaglie who had two shims on the stock needles and went to TBS needles and saw no power gain so two shims on the stock is probably the same in that respect as the TBS needles.
Most people are putting in the TBS needles to cure a mid-RPM slump as I did. You may or may not gain anything with these needles. What the heck, it's a cheap mod and easily reversable. The Thruxtons are too tapered for probably anything less than a big bore...
If you decide on the TBS needles, start with no shims and see what that gets you.
I have the Freak, Epcos, and ran the 160s for awhile and found them too rich. Now down to 150s and have not lost any power so I will do plug checks for awhile and adjust until I hit the sweet spot on the jets.
With your setup, the 130s and the TBS needles may be perfect. Do plug checks and even buy 140-145 jets for grins. They're cheap and it's downright fun playing with these awesome machines!!!
