http://www.ramaircraft.com/Catalog/Induction/414Ainduction/414ainduction .htm Lots of turbo exhaust systems to consider. Marc Wiese Look at the T337P. Go to RAM's website. Altitude makes no difference in this device, just absolute manifold pressure. Have you got a web address for this? A Google search yielded no results. S. Todd Bartrim Turbo 13B RV-9Endurance C-FSTB http://www3.telus.net/haywire/RV-9/C-FSTB.htm