https://www.youtube.com/watch?v=_PVXvHkr-Vs
2.5" is down 20hp/20ftlb along the curve compared to 3.0" on a 600hp combo, would think a 700hp setup would be hurting it more.
Maybe just me, but to reach 700hp would seem to mean optimizing heads (ported vs cast), compression, cam duration/lift...right to a high level. Then seems odd to go back and de-optimize the motor with small exhaust when there absolutely is an alternative with minimal drawback beyond being tougher to fit (but possible).
Now, if this was a street/strip combo where the exhaust is getting dropped at the track, that's a different scenario but I read this as street only.
Great video, especially the sarcasm about the old "an engine needs backpressure" urban legend.
Incredible though, to me, that all that 2.5" pipe ONLY killed off 21hp out of 622hp (if it was jetted rich enough with open headers to begin with).
That's only a 3.4% power loss.
So only a tenth or so ET and maybe 1.5mph assuming that Rat was in a Camaro/Nova.
Seems that good old Glass Packs / Cherry Bombs from the 1960s-70s are still very hard to beat, if they're done right:
* Same pipe diameter as the exhaust pipe - no narrowing down
* Perforated, not louvered. Louvers are for fastback rear windows.
* Big case with lots of glass to cancel noise & waves.