Cferrel4

That is because she does... I have a 02 Formula with 23k original miles on it and a 05 GTO that are both standard. She can not drive a standard. So it is more for her to drive around in the summer then me. I do drive it once in a while, when I feel like being lazy and not shifting...

JROC

Oddly enough lowering springs cured the vibration I was getting with my stock setup at less than 33K miles.

That or something I changed did:

I added MWC SFC's, Hellwig F/R swaybars, Koni SA 4/4 shocks, BMR springs, Founders roto-ball LCA's, double rod-end adjustable panhard bar, and LCA relacting brackets.

Still using the stock stamped torque arm though.

Cferrel4

How much lower did you drop your vehicle?

JROC

It's supposed to be 1.2" but I didn't measure. I will tell you that I initially did the heater hose mod but it dropped my rear too much for my liking in relation to the front so I immediately jacked the rear back up and put the factory insulators back on. I like it. Stock my car would start to vibrate at about 80 mph.

Cferrel4

I left the insulators in when I did the drop. Hoping to get back to the car this week or next and put some new rear rotors in it and change the differential fluid.

Cferrel4

I changed the rear rotors last night since the one had some minor pitting on it. Still trying one thing at time. Drove it last night, still hearing this "womp womp womp" at highway speeds 55 mph to 65 mph when you let off the gas and are coasting. I doubled checked air pressures and spin balanced the tires.

Going to remove the rear differential cover and change the rear differential fluid this afternoon when the shop gets slower.

I feel like I am really just reaching for the stars on this one now. Maybe that slight change in pinion angle while the car was lowered was enough to create this issue.