No, if you hold a manual at 4k you wont be on full load and full boost, you wouldnt even be on full boost if you was bouncing off the limiter.

It makes the engine load as much as if the car was flat out in 5th up a hill, so its working its hardest, so the min you let off the transbrake and suddenly there no load it REALLY rockets off.

There no way of getting the car under the same load with a manual (itd stall) or an auto without a transbrake (its not the same as having 1 foot on brake n 1 on accelerator).

Later on il see if i can find some vids of turbo cars launching off the transbrake...

Youl need good tyres tho