Low gear set from A999 installed into 904. Anyone experience gear noise?

Pretty much during decell at lower speeds but exhaust may be drowning it out. I don't hear it any other times.
Edit....I also tried in reverse but couldn't quite make it out. May still be there but faint if any.
So decell lower speeds and goes away in neutral, try in D range and slowing down and when you hear the noise shift into 2nd gear and see if you feel the downshift, if you can then we know it was in 3rd gear when noise started, now try manual 1st at 15-20 mph and lightly get off and on the throttle to see if it noise changes pitch or goes away and comes back.