'89 Vert
 

Just bought an '89 vert with a Haltech turbo. It's a monster, but have two big problems:

1) I'm getting about 15mpg... is there any way of increasing this?

2) It smells horrible inside the cabin - kind of gassy, sometimes with a weird "peppermint" smell after the turbo goes up to around 10psi - especially with the top down. Anyone have similar issues?