Enging spudders and back fires at WOT.

I have had it for a little over a year. It has close to 72k miles on it. I bought it with around 56k. Same turbo. I did change the exhaust to 3" turbo back with no cat. It has been scanned many times with no codes showing.

Would maybe be best to scan/monitor LIVE data, while duplicating symptoms (helper would be good , unless your scan tool is capable of taking a 'snapshot'.

I've done the live data but I really don't know what somethings mean and don't know what they should be running at(short term/long term %, timing advance, MAF, bank 1/bank2). The ECU is also programmed by APR but I can't get any of their dealers to read it for me. They said the chip is soldered in and they don't have the equipment to read it and APR is not much help either. Why no love the B5s?

Sorry , I'm not much into the 'tuner' stuff. Waaay to old for that!sounds like you might be stuck finding a shop that specializes in those types of mods. Might seem pricey at first , but if you can ask around and find a place with good references, that may be well worth it in the long run.