I have a SLP longtubes with high flow cats. I just picked up O2 sims. I just need to pick up some stainless pipes to put in the cat area. And I picked up the O2 bungs also. I was just wondering if I would need to retune the car. I just had the car tuned and do not want to have to go thru that again. I figure I would pick up a little more horsepower also. Please give me your opinion.