Some people think they will heat up easily.... yea i agree, but mounting any solenoids under the engine comparetment is gonna get hot...They do not touch the manifold at all, but they are close! Seems like so many users mount their's off the fuel rail screws...Opinions please
Don't worry,my WOTswitch looks like crap and is getting moutned else where, im still in the middle of wiring everything up!

 

I've had mine in that vicinity for years with no issues...

 

They should be alright (I had some there for a little while but the less heat soak the better.... You can take a folded, or boxed and glued, (to make it look nice) piece of dyna matt (summit racing has it).... or that silver reflective stuff that summit racing also sells to insulate starters from excessive heat soak.....Either will keep the solenoids much cooler.......I use the stuff summit sells for starters on mine and it keeps them just luke warm even after driving all day

 

It will be no problem mounting them there.
Dave