All with the L26 3.8L 3800 naturally aspirated engine, 2004-07 Grand Prix with the aluminum upper intake.
The High Velocity Upper Intake Manifold Insert replaces the factory plastic runners in the upper intake manifold found in FWD 3800's. Simply remove the upper intake (leaving the throttle body attached), pull out the stock runners, set the HV insert in the intake and bolt it back down! 30HP in 30 minutes!
More reliable - The HV4 does not require RTV, cannot be seen by anyone looking at your external engine, and it comes with a new intake gasket. Installing the new HV4 actually improves the reliability of your car by replacing a potentially worn out gasket. Because it sits entirely inside the intake, there are zero sealing issues.
Does not work on factory GTPs or L67s or F-body. FWD L26 only Does NOT work for the supercharged engines. This is the biggest horsepower gain for the money for all naturally aspirated 3800 Series L26 engines with the black upper intake plenum. Fits all OEM factory GM upper intake plenums and many aftermarkets. Does not fit some Dorman intake. You simply pull out the factory runners that slide out of the factory plenum and install this insert in place of it with the included modified upper intake gasket. This gasket alone is $30 and is included in this package deal. The Red one is for the 2004+ newer L26 aluminum intake plenums. This is made in USA in a high quality poly urethane material. They last forever and never go bad. You will feel the increased power in the upper RPM
Includes:HV4 insert & Upper intake gasket