I just installed NM clean air kit on my R55.

I went thru every step or so I thought. Now when I let my foot off the accelerator it sounds like a air shifter for a semi. It seems to becoming from under the dash, center. Any ideas?

 

Thats the "blow off valve" it's normal. You normally can't hear it because of the factory filter box. It's coming from the engine bay. Nothing to worry about

 

Thanks, next project is the cat back..

 

Yep it's pretty normal.

 

Pretty normal, and cool!

Just watch, all the Honda's with the unpainted body kits will be so jealous!

 

I too have the NM CAI and that sound was precisely what I was going for! sounds amazing... its actually the stock bypass valve, with a more accentuated blow off now because of the higher flow.