Intake question

[bgloworm22]

Will a ls6 intake manifold fit an 03 5.3 flex fuel?

 

[JennaBear]

With modifications yes, but you wouldnt see any gains.

 

[radkon]

LS6 intakes are designed for high RPM horsepower not low end torque. The 5.3 is designed for low end not high end. Without reworking the engine (heads and cam) the LS6 intake would pretty much be useless. I'm pretty sure you'll also have issues with the accessories interfering with the intake opening too.