i have 1999 K2500 with a 454. 6 month old Bosch injectors, new fuel pump and just got new exhaust put on and passenger side pipe is missing it’s cat while driver side is still there. Driver side also has a leak at the cat flange. While driving fuel trims are normal and with 1-3% of each other but when I let off the gas the passenger side start shooting sky up into 20-30% positive fuel trims. If even hit positive 50% at one point which is as high as my scanner would go. I have no idea what going on. It wasn’t tis bad till I put on the new exhaust but still slightly did it. The cat was also missing before the exhaust, an help would be appreciated. Thank you all!