New gears installed, clunking noise??

I hope someone can tell me what it is. When i am shifting at about 2,500-2,800 just taking it light I hear a little clunk noise from the rear. the noise happens once i let out the clutch and start on the gas. The noise doesn't happen when I am on it. Also, If I am stopped and I put the car in reverse and let off the clutch without pressing the gas I hear the same clunk. Lastly, when I am in 5th and let off the gas till about 1,500-2,000 and hit the gas again I get a loud clunk. Just trying to tell you everything I heard last night.

Could it be too much backlash?

I called the shop to ask what this may be and my guy told me that my new control arms are most likely hitting the exhaust. The Steeda units are thicker than the oem. I am bringing it in on Sat. morning. He told me it was nothing to worry about. Whew!

He also stated that the gears are stout and don't be afraid to rip 'em!

I was thinking that was the case, but the shop would have installed a new set of spring isolators if mine were gone. Travis @ Mustang Services knows his stuff. Excellent shop. they re-aligned my exhaust and tightened my header bolts free of charge. That's how detailed they are.

I do notice how there is very little clearance between my new control arms and the exhaust so, hopefully it's just a matter of adjustment. The shop is going to put it on the lift saturday morning with me there to show me.