I have a 1990 5.7L @160k miles with the original pellet cat still on it. I still pass emissions and am satisfied with the way the truck scoots around. I would like to ask those that have swapped out for a newer honeycomb cat if you noticed an increase in pep, MPG etc? I have a newish Walker cat-back system on there and the engine is completely stock. I'm in California, so I'd have to buy the CARB version which adds $100. Just trying to justify/motivate the purchase if it happens to have any noticeable benefits. Thanks in advance.