Yeah true, the viscous is a good comprimise between theromos and fixed fans, but a thermo would have to be better.

i dont know if it would actually give it any extra hp, but its gooa put less strain on the motor since it doesent have to spin a fan.

A davis craig unit would be good, since they are usually faily slim profile, but they can be a up towards $150-$250, so going to the wreckers might be cheaper.

I have a pair of thermos form an old audi that are nice and slim and about 6" diameter, so try that.