Prodrive backbox salvageable?

[67911121km]

Hi all, 

Just got myself a 07 R Sport after sadly having to scrap my Bugeye GX - but it's nice to get back into a manual and have a little more power. 

Before leaving the Bugeye at the scrap yard, I did take a few bits off including lights, window motors, etc (all up on eBay now to offset the loss a little), also the gold Speedline alloys with decent tyres, WRX spoiler and the Prodrive backbox that had been crudely welded to the smaller stock mid pipe. 

Now, my question is about the backbox and a small area that's rotted away under the tailpipe... 

Can this be saved (bead of welding or something to fill that open wound perhaps)... Or is it worth saving?