If you have a turbo put it make sure the shop knows how to mod your IP and try to take it to a turbo/turbine nerd. They do the best work and can usualy be found running a small shop in an industrial area near an airport. It will be more than a regular turbo but it will kick harder.

If you do propane the upfront cost will be much less like $300-800 even less if you get used parts (used tanks and regulators are easy to come by). Compaired to turbo which start at $1000. However, you will have to build on a liquid propane tank and buy propane which is $1.80-2.50 around here. So, over the long hall (years/thousands of miles) propane will outprice a turbo unless you abuse the turbo.

My personal conclusion; if you got the $ get a turbo... i'll be running propane.

Dylan