Anyone have one of these? Grubbs says they sell more of them that the Z-tube. I called Unlimited Tuning and they said the heat dissipation is not really an issue with aluminum over plastic unless you are idling all day long, plus the inside of the aluminum is much smoother for better air flow (sort of disputes the effectiveness of their carbon fiber model which is rough on the inside). Anyway, it looks higher quality than the Z-tube and is just slightly more expensive. Comments? Opinions? Thanks.