That drawing is a bit extreme. Below is a pic of all three needles and I finally found the post by Deuce where he measured both the stock and TBS needles in 5mm increments (there was no Thruxton at that time). Here's the page in the archive:
http://www.bonnevilleamerica.com/message...echnical%20Talk
and here's the dimensions in mm. Clearly, the TBS is
thinner everywhere and would therefore be richer overall. Shimming may or may not enrichen the main circuit too much. Also according to Deuce, the TBS needle is 3mm longer than stock.
TBA ---- TBS
2.48 --- 2.44
2.48 --- 2.44
2.46 --- 2.42
2.42 --- 2.39
2.32 --- 2.27
2.21 --- 2.16
2.12 --- 2.05
2.07 --- 1.92
1.98 --- 1.85
1.91* -- 1.70
--------- 1.60*
(*) = tip
