hello !

can someone help me out with the definition of turbo lag. as i understand it is as follows:

you get turbo lag if the engine is at low revs where the turbo is not spun up, and you accelerate to a speed where the turbo gets spun up to operating speed. the lag is the very short time between opening the throttle and the turbo spinning up.

is there a way you could see turbo lag if you have accelerated throttle full open from, say, 2000 rpm all the way to 6500 rpm at any point in between AFTER the turbo has spun up in the first instance ?

I dont think so.

If the turbo is spinning and generating boost which is charging the intake manifold with high pressure air/fuel then you are on boost.

The only I can think you might be referring to s a loss of boost due a split pipe, or loose pipework. This loss of boost will feel like a huge flatspot.