I refused to believe it myself. Someone said it would be the cause, so I got under there with the breaker bar and tightened the **** out of them. It didn’t cure the clunk, so I tightened them even more. Still didn’t cure it.
I decided it could be movement in the rear bushes, so made reinforcing plates and welded them into the subframe, then cranked the living hell out of the bolts, and still the clunk didn’t go away.
I finally gave in and replaced the front bolts for new OE, torqued to OE spec which I believe was 50lbft + 90 degrees, and the clunk vanished instantly!
Around a year later of hard abuse and trackdays on slicks, the clunk returned.
I swapped out those front bolts again, and it instantly vanished and hasn’t returned since due to less track use.
It appears that on track using slicks these bolts are a consumable for me!
Scary thought, but it actually appears to eat them!