Designed for modified Gen III-IV engines, the Victor LS Series 90mm throttle bodies increase flow and horsepower in high-performance street or competition applications. Throttle bodies #3864/#38643 include a LS1 stock-style TPS and IAC. Throttle body #386403 does not include the TPS and IAC. Extra idle control is provided with the addition of an idle bleed screw. They have an LS1/LS2 flange that can be mounted on aftermarket LS1 manifolds with a 90mm opening as well as LS2/LS7 factory manifolds. They do not retain the lower water tube and are perfect for enthusiasts who want to use an LS2 or LS7 in an older vehicle with no fly-by-wire throttle.