Legacy short on power

Bh5 twin turbo estate 2003,piper cross,decat,rebuilt prim turbo.Well lads i'll keep this short,she has had fresh service a few months ago and fitted turbo today with new oil with my new mechanic (he has a legacy)now the car just has f all power and he was saying it's plugs or it fells like the injectors,he cleaned the MAF and said thats ok,and no boost leaks,computer not showing anything.Any help would be super

Whats primary turbo boost?

Whats primary wastegate %

Whats secondary wastegate %

What voltage on differential pressure sensor?

What voltage are you seeing on maf on full load?

On computer looking for codes wont tell much

Would you not have to change the spark plugs after replacing a blown turbo,as it was pulling oil into the top mount and out the exhaust

New plugs and shes running away better,thanks anyway dave for your input