Abently - with all due respect you have no idea - not only on the "cams" issue, but you also state "it shouldnt detonate with 20psi at 8:1 compression" - id like to know what brought you to this conclusion? What about if this bloke has pumped 40 degrees advance into it at peak torque with a shitty AFR at that specific point? Did you also know that this peak torque point is the highest point of combustion chamber pressure, meaning it will make it more susceptable to pinging under bad tune conditions? Did you also know that throwing a different cam profile into this matrix will change the dynamic compression ratio (google it, im sure you already have the browser opened looking up the afore-mentioned terminology), as well as changing the peak torque mean? How do you think that will sit with his shoddy timing curve as it currently sits? Would you be comfortable in changing the peak chamber pressure without changing your timing curve? Do you even know what that is?

FFS - if you dont know something, dont offer advice - this person may rely on your "mis"information and do something which may cost him his motor or his safety - how can you wear that on your conscience?

Back on topic -

From the symptons "described" and from a view of your dyno graph, i believe your problem relates to one or more of the following:

1) Timing advance curve - you say your advance is "0 at the dizzy" - im assuming you are referring to your static timing. Because you have a controllable ECU, this does not necessarily dictate that you have zero static advance. I would get a second opinion on the tune - consult another reputable tuner and get them to check both static timing and your dynamic timing advance curve. This may mean (as some have suggested) implementing a diminishing dynamic timing advance to effectively deal with the AFR and boost pressures at the rpm reference point \ boost reference etc.

2) Fuel problem - whether it be flow, pressure, injector duty cycle maxing out (doubt it but you should never say never), AFR again ? Mutlitude of things to check here. Support for this cause is the power dropping off, although i suspect the tuner should be astute enough to pick this up in his tuning and determine whether you were leaning out - but still - better safe than sorry

3) Boost actuation problem (whether it be wastegate or EBC or a leak at high boost due to piping flexing under torque\gaskets leaking at high pressure\hairline fracture somewhere in the exhaust manifold not allowing boost to be held - ???)

4) Turbo compressor - not efficient\running out of steam\become innefficient and thereby causing heat, which is causing high intake pressures, and thereby meaning lower timing\more fuel required to counter the risk of pinging?

5) Mechanical problems - ie faulty plugs, faulty leads, weak ignition signal at high rpm, faulty CAS, faulty\weak fuel pump, coils etc etc.

Hope this helps - definitely need to see the same\ another tuner for another look.

Good luck
Mick