Just thought I'd share this mod that I did ( years ago so I know it works ).
Firstly, the idea is to get some air to flow through the coil pack area while keeping the cover fitted to stop crap from ending up in the plug holes.
It's very simple but quite effective.
Simply remove the upper cam belt cover, use a hole saw to cut one largish hole and then another smaller hole below and then remover the middle bit to make one teardrop shaped hole. Clean up the edges and hit it with some touch-up paint. That parts now done.
Now, behind the cam gears is the tin shield seperating the cam gears from the cam valley area ( where the coil packs are ). In there are some louvers ( from the factory ). Just carefully open them up more and the jobs complete. Simple huh
Here's some pics of the finished product.