Juice Box <does not equal> Car
I'm sorry but I fail to understand the premise of this thread. Are you asking if Terry Burger has a team of M engineers with him, to pseudo-tune the N54? Are you people suggesting, that somehow his hack (ie: piggy back), is better than what BMW Engineers can do.. even when terry & shiv are un able to access all the ALL the engine's perameters..?
A tune is more than about horsepower & terry & shiv do their best, but (again) they are not engineers & neither of them have control over the engine, just a small variances. Thus BMW engineers have fundamentally more to work with on their tune.
So, a piggybacked 135i will never equal a 1M in terms of power delivery, because piggybacks are inherently flawed, as they are not as in-depth as a real tune.
More phun added to ur 135i... aye. But no, you cannot compare JB add-on piggy back, to a full blown M tune. The comparison is apples to oranges.