I spent several years installing high end car stereo systems and have made many cars much quieter than when they rolled off the assembly line. I will document everything I do for ya guys though.
My approach will be a BUNCH of dynamat-like products, a layer of something soft like foam, then a layer of a firmer sound barrier material, then the typical under carpet padding/insulation and some new carpet. This approach is normally good for a 5+DB cut if road noise in a modern car, I'm sure it'll be much more effective on a mid-80's truck. The soft top doesn't help, but I did a ******* fiberglass '33 Ford once and when I was done you could easily have a conversation inside it at 60 mph, before you nearly needed ear plugs.
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I'm curious though, I installed a remote start and the only problem I have is resetting the choke before each attempt to start the engine. I'm thinking there might be a way I use the cruise control to do this for me. Is there a wire I can send power to that will cause the cruise to pull the throttle? If so, will it release(close) the throttle when I cut power? I can use an output on the alarm to trip a relay each time it tries to start the engine. I'm not really familiar with the cruise system so I'm not sure if this is possible. If I have tell it to close the throttle, I can use a second output on the alarm to do that too.
If I can't use the cruise, then I'll just have to figure out how to mount a physical solenoid to give the throttle a tug. But I'd rather use a factory part that is made to live in the rough environment found under the hood.