UK Triumph TR5 is 150BHP, US TR5 just 111 BHP, why?

[M5Rick]

Lighter and probably quicker than a TR6 PI it is worth much more than the 6.

[inverse121]

TR250 in the US is probably the most desirable Triumph, likewise the TR5 in the UK

Different camshaft and Lucas fuel injection over the stromberg carbs make the TR5 more powerful

Properly tuned TR250 with the “Pi” camshafts is no slouch… remember it weighs in at just over a ton.

For those that don’t require originality, Zetecs and Duratecs turn Little British Cars into pocket rockets.

[M5Rick]

That power bulge for instance on the drivers side showed that with other things Triumph had the drivers involvement foremost in its mind and as the vid shows Triumph were forced to come out with the TR6 sooner because of the coming influx of foreign cars like Datsun's 240Z, making the TR5 PI/250 the most sought after of all Triumphs.
Apart from the Surrey tops, having the TR6 hood with the zip rear window made these more fun to enjoy.