FWIW, a projected nose plug is generally "better" for two reasons - the projected nose is further into the combustion chamber and therefore can provide a better ignition of the mixture. Also, it has a wider heat range than a standard plug - it runs "hotter" than a standard plug at low speed/load, which reduces fouling and cooler than a standard plug at high load because the projected portion is further out into the incoming air stream. At higher RPM that has a major cooling effect on the plug and, therefore, the combustion chamber/related parts.
OF course, depending on combustion chamber design/piston clearance, a projected nose plug may not fit. For racing purposes, the wider heat range of a projected nose plug is not generally an advantage since the engine load/combustion chamber temps is fairly constant. A projected nose MIGHT be or might not be - depending again on combustion chamber design.
When we built performance engines, on the dyno a PN plug would produce more HP from a Mopar 426 Hemi every time over a standard plug of the appropriate heat range regardless of whether it was a 6000 RPM street engine or a 8500RPM competition engine. We thought 8500 RPM was pretty hot stuff a few years ago but those same SS/AH 426 Hemi's spin 9800+ RPM today!
