First, as other have said primary pipe 90deg to the gas flow is not ideal
Secondly, looks like the primary pipe for the gate is smaller than the v-band and then the screamer pipe is smaller than the v-band?
So while you have a 38mm gate, you are putting a restriction before and after the gate.
I would start by getting a bigger primary pipe and screamer pipe to actually the same size (or slightly larger) than the v-band