Hey Guys. Really need some help. My Aristo Swap 2jz gte twin turbo IS300 had 3 inch straight pipe with catback at 14.5 PSI. Unfortunately, I had to change my exhaust to 2.5 inch with filters due to law issues and I saw the PSI drop to 7 PSI and I have lost significant power. Is there anyway to get back the boost which I had before without changing my current Exhaust?