I’m driving down the freeway and I notice my car is droning and a loss of lower. There is a rasping sound coming from the engine. This happened a week after i installed a motordyne plenum spacer. Any idea what might be causing this?

 

Sounds like a vacuum leak, and it's likely some bolts weren't torqued to spec after the plenum spacer install. You can let the engine idle and spray the intake manifold with water, and see where it bubbles and hisses to see where it's leaking. Following the torque pattern is important as well, it's on page six of the manual. Here's the link, just in case they didn't mail it, or if you bought yours used, and don't have one. https://motordyneengineering.com/manual.pdf

 

Maybe a vacuum hose came loose. Because everything was fine then after like 50 miles I started experiencing problems. I think maybe it could be the cam position sensor going out if no leak.

 

Sounds to me like a broken catalytic converter. There is no reason that Motordyne would cause a sudden loss of power.

 

A rasp/drone is very unusual for a plenum spacer install. Helsinki might be onto something. Can you recreate the noise while parked in neutral? If so, snap a video and upload it.
-Icer