I have one and I'm very pleased with its performace. I was worried about the amp draw but neither one of my converted cars have been affected. I have it after my filter and before the ip. I also added a gp heater before the filter to ease the flow through the filter. I would have liked to use another Vegtherm but I know that would be way overloading the alternator. All in all I'd say its a good heater.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo