My friend and I decided to see how much of a difference the Utec (+catback) makes versus stock. He has a '04 wagon with Utec + Borla Hush catback, I have a stock '05. Went from a 2nd gear roll around 3k rpm, and stopped at top of 3rd gear. At the end, he was atleast 3 carlengths ahead of me, and would have continued to pull farther had we gone faster.
Guess thats a pretty good improvement over stock!