You may try to adjust the pressure to match the FGK exhaust setup. Petrol smell at the exhaust tip means waste of un-burnt fuel.
Btw, was the O2 sensor relocated at the same factory default spot?
Take Campro CPS engine for example. Many aftermarket extractor had the O2 sensor located next to the block (as in 4(O2 sensor)-2-1) which can be seen from the engine bay. This may sometimes caused unbalance af ratio reading (rare case but coupled with other mod, you may in for a lean reading).
The original setting if am not mistaken is in 4-2(O2 sensor at the end)-1. That is why you will not see the O2 sensor from the engine bay on R3 extractor as it had been relocated to factory default spot.
Another mistakes which going unnoticed when changing extractor are the cylinder's firing order.
Standard Campro CPS firing cylinder is 1+4, 2+3, but some aftermarket extractor has 1-4,2+3 (1 stretched is longer than 4).
It works but there might be a slight compromise in performance. Part of the reason why people complain about increased fc while performance decreased.