Yes the compressor fits in place of the euro5 canister and the trumpets where the normal horn mounts. Been using it for 2 years no probs. Grease all connectors and place relay up high to avoid problems during water crossings.
Follow the tank breather pipes and you find a black long box down on the right hand side of the motor. You will need to take the tank off (easy job) and then it will be clear.
^this will get you the general idea for sure. Though I'd suggest just leaving the OEM solenoid in place rather than messing with buying a dongle. The dongle just replaces the solenoid so the ECU won't complain about it missing, and there isn't enough size difference between them to matter.
Did you have any issues with canbus warnings when removing the original horn to feed the relay of the Denali unit or was it a straight fit and seamless integration?
