I just had a new engine (351M) dropped in my 73 vert and was wondering about what type of exhaust I should put on. My mechanic has Flowmaster 40s real cheap - but I'm leaning towards glasspacks. Do I go dual? single? Packs? What do ya'all have on yours and how do you like the sound? I have flowmaster 50s on my F150 and it's nice, but too quiet for the 73.