Ever since remap I have had a strange noise on over run. Seems to be coming from gearbox but not sure. Seems louder in 3rd gear. It sounds like a loose heat shield but there are done (wrapped headers etc)

Does it more when warmed up but only at certain revs as you slow down.

 

Most likely a transmission noise/resonance.
May be nothing. Check the gearbox and diff oil levels. What oil are you using and has it been changed in the last 10k miles.
Get the car up in the air and check the security of EVERYTHING underneath.

 

I have the exact same problem (ukturbo97) in 3rd and 4th gear on over run approaching roundabouts. Only had my 2nd hand gearbox fitted about 4 months ago! hope its not that. Let me know what u find, its been doing my head in for the last 3 weeks.

 

Cheers Harvey, think i will drop the oils next week and see what happens.

 

I'm guessing its the box as there are no heat shields on mine, not good but hey thats scoob box's. I always thought the ra box was stronger but Andy F says not. I may look at an sti box but sure if that mens swopping rear diff.

 

Obviously, ensure F and R diffs are the same and remember Jap cars had a 1:1 drop gear and UK cars a 1.1 :! droppper. So for instance a Jap car could have 3.9 diffs and rear or 4.11 or 4.44 whereas UK cars had a 3.9 front diff 1.1:1 dropper and 3.545 rear diff which with the dropper becomes 3.8995 which I guess is close enough for farm work.

The other thing you can do is use a magnet when you are dropping the oil to pick up any swarf from either the diff or gearbox. I permanently run a magnet on both the gearbox and diff drain plug to pick up any swarf. Expect to see quite a bit of iron filings if it is some time since you have done diff/gearbox oil change.