Bobby Knauber compared KKM (gauze) and Monster Flow (foam) side by side on his SE V6. KKM was 2-3 HP better from 4000-redline. Dynos posted somewhere. High flow SVT heads /intake, bigger throttle body, etc. may allow greater gains on SVT.
1999 Amazon Green SVT Contour (#554/2760) Stock SVT Duratec V6 with: Intake- K&N filter/75mm MAF meter Exhaust- MSDS Y-pipe/Bassani catback Durability-Ford "dual mode" damper, Mobil 1/K&N oil filter 179.2 FWHP at 6900 RPM