As an ex tuned 16V owner - and with the very greatest of respect - my old "171bhp" 16V probably really ran about 155bhp as I found out when I had it RRd myself. The torque was also about 130lb/ft at peak, perhaps 110lb/ft at 2500rpm if I recall correctly.
Again, with the greatest of respect, I cant see how even a massively tuned F7P 1764cc could make 189lb/ft of torque at 2000rpm. Im sure someone like BenR could explain further, but the very nature of the crank and multi-valve head make it pretty much impossible without some serious, serious work. The power, maybe... just maybe - but that much torque, Im still unconvinced.
I understand that youll think what else can you do to prove this as youve already had a RR power run done, but I think youre going to have a bit of a surprise at the next RR day you go to. Where was this tested and what are the at the wheel figures?
My old Valver probably wasnt much slower than my standard Willy is now in a straight line, but the torque spread on the Willy makes it quicker in real life. If, as the RR claims, yours now makes 189lb/ft at 2000rpm, then you have a true Williams slayer. In fact, itll kill any Cup, 182, 172 and probably V6s if you really do have 189lb/ft at 2000rpm.
Suffice to say that Im the first Williams owner in the line to offer my car as a basis for comparison!
(providing youre not too far from Wales!)