Which Flowmaster:

[c00nhunterjoe]

Bit different on the track where it's all max revs and flat out...on the street you will want back that midrange torque that open pipes loose. A little back pressure will help keep the fuel in the cylinders on valve overlap and help with flexibility and midrange.....far more useful on the street than finding every last horse imo.

Adding an x pipe to gain 2-3 hp is finding every last hp imo... my car launches at 1900 rpm. I would count that as lowend and flexibility. The avg dyno almost always starts their pulls in the lower midrange rpm. In my builds i look for max power across the entire range, not just peak. Show me legitimate dyno sheets with back to back testing of open header, collectors, and full exhaust that shows me the full exhaust making the best numbers.

[alfaitalia]

Bit different on the track where it's all max revs and flat out...on the street you will want back that midrange torque that open pipes loose. A little back pressure will help keep the fuel in the cylinders on valve overlap and help with flexibility and midrange.....far more useful on the street than finding every last horse imo.

Specially for you...
https://m.youtube.com/watch?v=jjPeP_Nn2B4

The man is an idiot....he does not allow for any valve over lap ...be clearly says "when the exhaust valve closed and then the inlet valve opens".....when was the last time that happened? 1935? It's great to expel all the exhaust gases...but not if it's taking half the incoming fresh charge with it.

[alfaitalia]

Bit different on the track where it's all max revs and flat out...on the street you will want back that midrange torque that open pipes loose. A little back pressure will help keep the fuel in the cylinders on valve overlap and help with flexibility and midrange.....far more useful on the street than finding every last horse imo.

Adding an x pipe to gain 2-3 hp is finding every last hp imo... my car launches at 1900 rpm. I would count that as lowend and flexibility. The avg dyno almost always starts their pulls in the lower midrange rpm. In my builds i look for max power across the entire range, not just peak. Show me legitimate dyno sheets with back to back testing of open header, collectors, and full exhaust that shows me the full exhaust making the best numbers.

Fair enough...but I don't really think that a drag race car can be compared to a daily driven street car. The couple of times I've fitted straight through exhausts on cars of mine I've noticed poor off idle to midrange response and excess unburnt fuel in the exhaust gas analyzer. Neither of which would concern anyone on the track. These were more modern (1990s) cars with higher rev ranges it must be said.

[c00nhunterjoe]

Thats odd seeing as how the arguement for exhaust and mufflers is straight through design by all manufactures and all performance categories.
   Were your 90s cars retuned after each change? Early eec processors could not adapt to changes and needed reburns for modifications. Even eec 5 and modern can systems need reflashes for aftermarket upgrades.
   Fwiw, my "race" cars are street cars. I could drive them daily if i chose to and if the weather is not unbearbly hot, i do drive them near daily. And aside from my race cars, my 07 5.7 hemi charger was pure stock other then exhaust and my own written ecm flash. On stock 245s (not drag radials) i was running 13.0s with 1.8 60'. Stock manifolds, stock 2.82 rear. 150k on the clock. 2.5 inch exhaust, ultra mufflers... h pipe. I ran the x at the track with the h back to back and saw ZERO change. Graphs were identical, af was spot on, even tried tweaking, no improvement.  To note- that car went 14.0s as purchased. 13.80s after bolting on the new exhaust. The rest was laptop time.

[alfaitalia]

I'm not disputing that straight through pipes ultimately give the most peak power....but at what cost? Usually at the cost of a loss of low down torque...which is where a street car needs it. That's why lots of newer cars (and for many years on bikes....my Yamaha FZR 1000 had a gate valve in the collector on 1989!) have valves or flaps that partially close the exhaust at low revs...to minimise low revs torque.. To me the area under the dyno curve is far more important than the peak number.

[c00nhunterjoe]

Im not aware of modern cars using restrictor flaps in the exhaust with the exception of volkswagon and audi. And i dont count much that they do as it is expensive and never works. Area under the curve is important on every engine except maybe rotaries. And i dont count those either....lol