etlsport,
I ended up putting the ballasts on the bumper side of the radiator bulkhead because there was more room there and I was tired of tearing my hands up trying to jam them in the engine compartment.
I did mount the relay for the system on the engine bay side of the radiator bulkhead because it needs to connect to the battery and one of the original headlight plugs.
You can run the wires to and from the ballasts through a grometted (sp?) hole at the lower outsides of the radiator bulkhead.
Both ballasts installed on bumper side of radiator bulkhead.
Driverside ballast. Grometted hole is at the lower right below the ballast.
Relay mounted to engine bay side of radiator bulkhead.
The ballast brackets in the kit I bought are pretty flimsy, so to make sure that I didn't lose a ballast while offroading in Moab, I took Ldub's suggestion and drilled a hole on either side of the ballasts and zip tied them down.
Let me know if you need any more information, or if you need more pictures.
Oh, forgot to say that if you do mount the ballasts this way you will have to move one of the stock horns on the passenger side (there is one right where the ballast is located on that side). I just extended the wire and mounted it to an existing tapped hole just below the horn that is closer to the center of the VX.