I like the zippy performance of my B16 544, but I think it is more a factor of the 4.56:1 rear end ratio than the power of the engine. Most parts are still obtainable. The car is a lot of fun on twisties and backroads. To me, it is best up to about 50 mph. It will keep up with highway speeds no problem (65 mph) but gets quite noisy. I imagine it is spinning about 37-3800 rpm around there.

I see the weak link in the gearbox. B16s used the M4 gearbox and it is very much like the later M40, however you cannot get some parts like the layshaft, spindle and some gears. You cannot attach an overdrive to the M4. A M40 will not attach to the B16 bell housing without modification.

All in all, I really enjoy my B16B. But I don't think I'd have the same opinion if I had to use it as a daily driver since I spend the daily commute on the highways. I also like the somewhat uniqueness of the B16. I have no reason to say it is a bad engine, just not as robust as the B18 or B20. If I had to rebuild the B16 again though, I'd more likely change to a B18 or B20 instead.
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'60 544, '68 220S, '70 145S, '72 144E, '86 745T