2.5 complete exhaust VS a 3.0 complete exhaust

After a decade dyno-ing motorcycles, I have a couple observations that are relevant. We did a few thousand exhaust swaps in that time.
Note that I just put new exhaust on my car, and it runs great. I did not dyno before and after. Why? Because I don't really care, as long as it beats up on ricers.

#1. If your vehicle has a dip in midrange torque, it will feel faster. Why? Because it feels like it's "coming on the cam" when in reality it's just getting to where it's running "right". A full torque curve feels much slower...but in reality is much faster.

A LOT of aftermarket manufacturers sold their goods not because they made the vehicle run faster, but because it felt faster. On a street car, this may not be a bad thing to an ignorant driver.

#2. Simple fluid mechanics is what it is, and there's no real reason that X pipes or H-pipes wouldn't add power. I'm not saying they do or don't, just that there's nothing that says they will not.

#3. I go by empirical evidence whenever possible. That rules out a lot of maybe's. Mopar Action had a proven dyno increase in peak power on their Bold Beeper 'Runner. See note #1.

Increase in power, and increase in peak power are two WAY different things. If you could have 500 horsepower from idle to 6000 redline, or 100 horsepower from idle to 4400, 900 raging ponies from 4400 to 4600, and 100 horsies from 4600 to 6000 redline, which would you choose? Which one makes more horsepower? One has more overall, one has more peak. More importantly, one is easier to brag about.

So, where are the x-pipes, h-pipes, no-crossover, etc. making power? A drag racer is going to look at peak power and little else, a road racer looks at midrange and little else, and a street driver looks at magazines and little else. Which one are you? What is it exactly that you are after, and what exactly is it that so-and-so told you, and what exactly were they after when they did their research?

Again, not saying wrong, right, or indifferent...just advising people to ask questions that may help them get what they want.