typically the amped up throttle response is responsible for 80 percent of the subective feeling of being "faster" for any naturally aspirated tune. Fact is if you ran them side by side, a stock vs. tuned. Each with HFC xpipe. THere would be zero difference in any tests-rolls from 20-100, ,40-100 etc.
The other 20 percent includes 15 placebo and 5 percent from the extra 8whp.