vtraudt

My 2.7T APB has 160k, dealer maintained, no issue. Nevertheless, it won't last forever. Currently stage 2, close to MAF limit (280 g/sec).

52lb injectors, 85mm MAF, K04 standing by. Engine out scheduled for install.

Down the road: FMIC, clutch, cat back, RS6 turbos.

Decided to buy used 90k APB (not in car)as 'spare'.

a) Looking for opinions if I should install K04, injectors, etc. (timing belt if not done), etc. on new engine and install and use current for built/upgrade for future power upgrade?

Or

b) Put K04 etc. on current and strengthen/improve new (lower mileage) engine? Swap in when RS6, intercooler, clutch, cat back, etc. are 'ready'?

c) What can be done to the APB to 'better' it with respect to handling more power (I would hope the RS6 are good for 500+ HP)? Bottom end, top end, else?

And

d) Longevity (on either a 160k or 90k engine). Bottom end, top end.

Keeping Bang-for-the-buck in mind (i.e. big $$$ items for minor gains are not high on the list).