SLR55
you are right
but the advantage of the H pipe that it does not need clearance compared whith the X pipe

tip:
when installing a higher camshaft lobe with a higher rocker arms ratio
to istablish a higher valve lift
every one must consider the clearence of the valve retainer wich we can solve by installing a smaller valve retainers
and also we might consider changing the vlave springs to a stronger vlave springs if we are thinking of revving the motor to a higher RPM