I think some of this hinges on your model S70. I have the high pressure turbo (T5) and I noticed a slight improvement. (nothing big)The S70 uses a large air filter relative to the engine displacement, consequently the turbo models would see more of an improvement as they require more air. That being said I have used K&N filters in my 1997 Eagle Vision TSi, and my 2000 Chrysler LHS, all have performed well and have lasted more than 130,000 miles in both vehicles, my '98 S70 has had it's K&N for 89,000 mi, no adverse effects...