BTW the problem is even worst if you throw in FI or N2O into the mix. You are stuffing more air volume and the importance of removing all that extra air once it's been burnt out of the chamber becomes even more critical. There's an even higher chance that more burnt gases will stay behind in the chamber, instead of leaving as they should, with a piss poor exhaust system sizing, when you do a SC or turbo. More stays behind, more dilution occurs, less combustion efficiency, less power.
The biggest bling bling gain in an SC car (after the SC itself) IS the properly sized exhaust system.
repeat after me: an exhaust system releases power and doesn't create it...an exhaust system releases power and doesn't create it...it's a good mantra to understand....
the newbies that whine over the 2 whp "gain" they got from their $800 great sounding exhaust are the ones that missed the big picture. they can't see the forest from the trees...