Just did it the other day on my '87 TD. Reads from 5-15 psi between the posts. No increments, but the red zone begins at ~10psi. The car is still up on blocks receiving an intercooler among other maintenance items, but the mod has been completed, so I'll report how well it performs later. I used the bourdon tube assembly from an '89 300E and the gauge face from an '86 190E 2.3 (no "Premium Unleaded Fuel Only" script). I have no intention of tweaking the boost level beyone stock, but may use the boost controller to maintain proper pressure at the manifold to compensate for losses through IC/plumbing.