i have a 1989 mazda 626 lx touring sedan and i have 2 questions. first, what is the spealer size in the rear? i have a hatchback and the crutchfield.com website said i had 6 1/2" round. is hat right? i dont remember. and also, i saw a service bulliten about my model of car idleing a little rough when in drive and sitting still. mine does that. i dont know why. she runs great though and all the belts are new and i have replaced lots of stuff but i dont know what the deal is. also, she shifts great too. just idles rough a little. thank you for your help.