I have a 05 Z with single intake and the intake manifold has dark spots all over it. I would describe it as discolored. I'm afraid to try to clean or polish it since it is not a smooth surface. can i get some advice? anyone with a 03-05 also have this issue? everything else in the engine bay is super clean!

 

I have an 03 and I too have little dark spots on mine. Looks like little burnt spots I'd post a pic but she under the cover right now

 

I know what you mean. I had this problem about 5 years ago and I used Nevr-Dull to remove the spots. It worked well and I have used it a couple times since and the intake remains spot free.

 

I painted mine wrinkle black after a good cleaning and scrubbing. Looks a MILLION dollars better!

 

Post photos and we can help you.

 

i will post some photos of before and after:

step 1. clean/degrease with simple green

if needed, step 2 metal polish/cleaner