I can tell you from my experience....my jambs, trunk, engine compartment, passenger compartment, interior firewall and inside the door panels is all single stage Polo Green Metallic. I painted them myself. Its the exact color that my paint guy sprayed the car with in the 2 stage version. You can't tell the difference, its cheaper, its faster and b/c I painted it, my paint guy didnt have to open any doors or climb in somewhere to paint. 12 yrs later the paint is still the same. No expense was spared in the restoring my 69. The inside of the heaterbox is painted, the bolts hidden behind the dash are all grade 8, allen, or stainless. Since its already at your paintshop and he does it for a living go ahead and have him do the 2-stage....but when you are working in the engine bay and you drop a wrench by accident (we all use covers and blankets but sometimes we just wanna "do something quick") it will happen...a crater