Here's a picture of two Viper air filters, one S&B (top) and one K&N. The main differences are in the filter area. Both air filters use the same cotton filter media (same thickness too). However, the S&B brand filter has deeper pleats and an improved manufacturing process that keeps the outer rubber seal from bleeding into the filter area. This larger filter area yeilds lower restriction and accounts for the "whopping" 2 HP gain over K&N's on a Viper.
Both filters can be cleaned and re-oiled using the same products and each carry a million mile warranty. Either brand filter should be looked at after about your third oil change and cleaning should be done at around 12,000 miles (sooner in dirty dusty operating conditions).
We, Roe Racing, offer the S&B brand filter because it's a better product and we can provide it at a lower cost to Viper owners than K&N's.
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P.S.
We even have the S&B's with a short foam "pre-filter" in front of the air filter (like your stock Viper air filter has), for those that do operate their cars in dusty / dirty areas. In stock.