Does this sound like my exhaust may be too restrictive?

[Codeman96]

While changing my valve springs I notice when I popped the exhaust valves to seat the locks that I was getting pressure out of both heads from the exhaust crossover. Seems to me that the flow should go on out the exhuast and not reverse back up the opposit header. Am I wrong here? If no more pressure than I had in the cylinder to change the springs was backing up what is it doing when the motor is running? I built my own 2X 2.5 into 3" y pipe and I questioning my design now. I need some input here guys should I go with dual exhaust or order one of Flowmasters high dollar y pipes?

 

[HarryH3]

It's doing exactly what it was designed to do. The factory setup had a flapper valve installed at the end of the passenger side manifold. When cold, a spring would loghtly hold the valve closed, forcing some of the exhaust back through the crossover in the intake. That would heat up the intake quicker for better emissions. Once hot, the valve would open all the way, but any pressure imbalnce can still pass though the crossover.

 

[Codeman96]

OK that makes sense. But I don't have the factory flapper valve. It was all removed when this motor went in. Hence is my exhaust not flowing enough?