Fast depends on what stock intake your comparing it to, & what the purpose is. If your comparing it to the stock LT-1 intake of the early 70s, than no, it isnt any better. if your comparing it to your typical 4 barrel intake on most cars & trucks of the 70s & 80s, they are better. The differance is most noticable over 5000 RPMs in most cases. a typical 350 Chevy in stock form made power to about 4500 RPMs, so the stock intake worked fine, if you bolted a Performer to that stock 350, you probably wouldnt notice much, if any change. John