the RPM ranges that the manufactures claim are estimtates at best, get you in the ball park.a Performer intake is advertised from idle to 5500 RPMS for example, if you put it on a small motor like a 283 or 289...itll make power well past 5500.
The Stealth is a good intake, Wieand claims the Stealth makes power from idle to 7000 RPms, while Edelbrock says 1500-6500. Sure, the Stealth well run below 1500, but realisticallythe 2 are probably pretty equal.
now...pretty much any engine that is making power to 6500-7000 RPMs is pretty dead below 1500-2000 RPMs anyway, so it really doesnt matter.
If your running it to say 5500, the Stealth & the RPM will make better power from 1500 RPM & up...but a Stock or Performewr type intake will make better off idle to mid range power.