I have a VPS so i can alter my time out setting as I require so ill up my timeout and see what happens.

How ever when you making numberious files and then merging??? you can upload numberious files to google merchant centre you know... just need to give google the feed name. I currently export 5 xml files each with 500 product in and upload to google individually. All done via cron jobs on a night.

I do have an issue though with a product as the feed seem to fail on a product and halts but doesn't say when. Checked the product and can't see any issues with it....