Vista Blue Boo

I have a 2006 gt, automatic. I recently replaced the engine(170k) with another 4.6 13k. With the engine swap I put on long tube headers, o/r h pipe, and flowmasters. After the swap for about a month now, I feel a vibration at about 1600 rpm, 48-52 mph. I can feel the vibration in me seat and my feet. Already changed the drive shaft. Could it be harmonics from the opened up exhausts? The rear end has 3.73 gears and all the bearings and seals have been changed about a year ago. Any thoughts? Thanks, Boo

88 orangepeel notch

I would first determine if it's rpm related or speed related. If it can't be recreated at any other speed or rpm or gear, I'd start looking at the rear tires/rims. Maybe lost a weight, or picked something up. But at that low of speed, it would have to be pretty drastic, and then it would also get worse as the speed increases. I'm assuming ujoints are new with the replaced driveshaft.

Hmmm, I'd be curious as to what it is, post back when you get it figured out. Good luck