Boost leaks are exactly that - under boost, pin holes in hoses or loose worm clamps, something that would normally be closed off (ie on the rubber piece between intercooler and throttle body) will leak a bit. I had it on my engine once - I forgot to do up one of the worm clamps, and under positive pressure (boost) it would leak air. Things like this. Look around for any obvious signs like soot/oil residue on any of the inlet tract or manifold. I never took a photo of it, but it was pretty obvious when I did look around the engine.
Certainly is. You aren't reseting the tune as such, more so the learnings of the ECU. Reseting it back to how Sean gave it to you.
The earth kit just gives the sensors a more direct earth. It can cause issues with eddy currents, but generally it will do more positive than negative. Giving sensors clean earths will let the ECU read a cleaner signal. I'll post up a photo later today if I get a chance to show where I put mine. It should be noted here that on most dyno tests I've read about concerning this, these kits give a real, measureable 3 to 5 kw atw.
The BBOD is the black box mounted against the LH strut tower. There is a lot of vac lines connected to it. It holds all the solenoids that control the twin turbo system.
Oh ok, thanks for that info. Might take a look into cleaning some of the sensors then I think. I do think the leaks are something that they would have possibly seen when they stripped the engine/built it up again though. Might still be able to give that black box a clean out though as it doesn't sound particularly difficult.
Sean did say try not to change too much after the tune, as the tune is made based on the condition of the car when they get it apparently. I was thinking of changing the pod filter though, as the one on there seems pretty old and probably way too big. Would it hurt to clean sensors/replace minor parts post-tune? What's your opinion?
I would be worried about something causing that loss of power - mine makes 145kw atw with a tbe and on the stock tune.
Haha, yeah a few people have said that theirs made around 140kW stock. Must have been taken care of well imo, even Sean reckons that a lot of autos only make somewhere around 115-130kW. He said mine was a bit low but didn't seem to be concerned at all about any major loss of power. To be honest I think I'm gonna have to accept that I've realistically bought a car that hasn't been taken care of as well as most. The guy who had it before me was putting 95 in it (he only had it for six months though) but at the time alarm bells didn't go off.. that and I didn't have the knowledge that using a lower octane fuel could do rather extensive damage to the engine. Oh well, I reckon I'll just keep this one clean and up to scratch with all the servicing then eventually go for a nice premium pack GT with a FULL service history, no exceptions! 
