Actually, Triumph ditched the Solexes in favor of twin 150CD Strombergs in September 1965. With virtually no other changes, that added about 10 hp.
Aside from that, anyone who has driven a GT6 or a TR6 knows just how smooth the engine is, not to mention the available torque. Some folks have even claimed that the 1600 is the smoothest running of all the iterations of the Triumph six.
No, it's not a particularly quick car, and the stock final drive of 4.11:1 (same as Herald and pre-1971 Spitfire) may have been less than ideal, particularly for American highways. But it's still a very smooth ride...just not as nimble as a Herald (very similar to the comparison between Spitfire and GT6). And I would note that overdrive was available from the start, which is something I might do to my early Sports 6 if I ever get into restoring and actually driving it. Beyond that, though, it will remain stock, with 1600 and twin semi-downdraught Solexes. :wink: