There are systems developed by Eaton (and a few hot-rodders) that use both a blower and a turbo in tandem. The blower (small unit) gives boost under the curve, then goes into bypass and hands off to the turbo on and above the curve. VW has adopted the system for a small engine package:

Eaton Twincharger

Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum