Well said 4 Jaw.
Too many people become caught up in the peak HP number. Well, if everything up to that peak number is lower, then the car will be slower.
This is not only due to the scavenging of the longer tubes, but he gas velocity. Also, If the tubes are too large, low end will suffer. Yeah it will make a bit more power up top, but how much time does it spend there. On the track...probably less than 2 seconds. On the street...well it really never should. The majority of the work is done at below peak power. If power is higher in this range, performance will be better.