Bro,
Are u using Adjustable Fuel Regulator (AFR) that is connected by a long rubber hose from the fuel rail to the AFR.
This could be the problem as it takes a few cranks before it can build pressure to squirt fuel into the injectors, due to the long hose.
I was about to mention this when I was reading through the thread. But the problem is not about the long hose.
The problem is some of the after market adjustable fuel pressure regulator does not retain fuel after you shut down the engine. However, it can be tested with a pressure gauge. If the fuel pressure drops immediately after shutting down the engine... Fuel pressure regulator lar tu....
The stock FPR does not allow drainage within the fuel rail. Hense, the fuel pressure can be maintained.
Regarding the injectors, if u shut down the engine for 5 minutes, even before the engine cools down, the same problem will appear.
Exhaust..? what does it have to do...? When trasplant the engine, before pasang the exhaust the engine still starts on the first crank. Bising lar...
About the leakage of IC piping... U will feel the engine feels like wanna doe of even when u are driving.
All mentioned are based on persinal experience...