I have talked with Denso many times and they told me they do not have a plug for the viper and if you use a plug that is not for the viper application that they will not honor the warranty if the engine melts down, They also said DC will not too. They told me their plugs make the combustion chamber run way to hot on account of not having a projective tip. Skip White and I have covered this topic many times and have both done dyno pulls with different plugs. The Autolit XP's make your engine run smoother at idle, and reduce flat spots right up to red line. An added benifit is better fuel mileage.
-Technically speaking, just changing the heat range alone makes it a "non-viper" application. Seeing as an iridium plug is not even available in the OEM Vipers' TOO HOT 12 heat range, it is not even possible to get a true Viper application, even if a projected tip were available. Iridium plugs do not come in lower (hotter) than a 16 heat range. I stand by my "they will not void your warranty without MECHANICAL damage or INDUCED damage from the plug you used." PERIOD.
-While the absence of a projected tip does give less surface area for heat to channel through out of the combustion chamber, the colder heat range makes up the difference. However, you are only looking at the low-speed side of things. During heavy loads at high RPMs, a projected tip cannot channel the amount of heat it recieves, thus overheating- which leeads to pre-ignition much sooner than a non-projected plug. The whole "projected tip" idea is based upon low-speed driveability, as the plug tip gets hotter and does not foul as easily... high speed, heavy load, it is a no-no, especially in a HOT 12 heat range. The other thing a projected tip does is (in effect) advance the timing a couple degrees due to it being projected into the cylinder. This gives the "feeling" of more power and better reponse. Again, on a STOCK engine. A VEC-2 equipped car can get the best of both worlds with the ability to advance the timing back, and run a colder non-projected plug that will not cause detonation after tuning in some additional power.
On a side note: I recently uncovered that the RC12ECC used in the SRT-10 is available in an RC10ECC variation. At two heat ranges colder, (USA Heat Range Style), with all other configurations being the same, it may be "the plug" to use. Does not look to be readily available however...