Advance Flights Systems' manifold transducer has a 1/4" hose barb that needs to be conected to the supplied manifold pressure hose supplied with the VMP Install Kit from Van's. However, the supplied firewall fitting (VA-170) is for a 1/8" hose. The solution is to remove the small black plastic hose fitting and replace it with a new fitting with a 1/4" hose barb on one end and 10-32 threads on the other to thread into the VA-170. The fitting I used is pictured above in the middle of the photo. It came from McMasters Carr part number 5058K243 and is discribed as an aluminum single barbed tube fitting adapter fro 1/4" tube ID X 10-32 UNF male.
Here you can see it threaded into the VA-170. When assembling these parts don't forget to use a sealant such as Fuel Lube. The install is then completed by running 1/4" hose from the firewall fitting to the transducer. Click on a picture to see an enlarged view.