Ported IM and TB made a gain.
you should really look into shaving completely the top rod, making a divet in the blade, inserting counter sink screws, and just connection the screws to the bottom rod. You can also shave the bottom rod down a little to make it flow better as well. I see the picture on page 2 of the subaru TB but it can be done even better than that. I have never attempted one on a cobalt but it works on many others quite nicely. Here is a picture of one on a mazda



