Can I grind out the ridges on the plenum cover while I’m doing a polish or does the engine run better with the tumble effect? Not going to really touch anything near the injectors, I don’t want to mess anything up and the fuel keeps it pretty clean, but the plenum gets really dirty and I wanted to know if anyone has had any negatives from putting a nice mirror finish in there to help with buildup. I know I won’t expect much in hp gains, but I’m killing time until my rebuild kit gets here and I figured this would help with mpg if anything and let me take further advantage of the drop in filter until I can get the long ram intake through the driver side brights.

It's been done before but usually in conjunction with other things likes cams or boost in order to see any significant gains from it. Just grinding out the plenum won't give you much of anything. but if you're just killing time and wanna put in the effort then go for it.

this build has some pics if you wanna see how they did it.
http://www.6gc.net/forums/index.php?showtopic=83759

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Oh wow I don’t think I’ll be going that intense. The goal is just to help prevent that funk build up in the future. I posted some pictures of the before in my project thread, but they’re still in post purgatory. I’ll be sure to add the after when I’m done so they’ll all be up eventually.