Well on my old FBCS it was broken and it would run 17lbs. in 1st and 18lbs. in all other gears which caused me to hit a fuel cut and throw a CEL. I was thinking that having an 03' with the different OL/CL it would be okay to run around 16lbs at most without a tune. I've heard that I really need to watch out for PTFB but other then that I should be fine. This is just info I've been getting from nasioc.com Here's the thread Manual Boost Controller - Factory 2.0L Turbo Powertrain - NASIOC