I have a HP440, 400HP 500 Torque and the exhaust that is on car now is h-pipe and tail pipe are 2 1/4 . Should I upgrade to a 2 1/2 or even 3 ".

Thanks Tom C.

I have a 1969 Dart that had a 440 in it with 2.5 inch exhaust out of the 2.0 inch primary pipe Hooker fenderwell headers with a 3.5 inch collector headers to a set of old Corvair type Turbo muffs and then to a set of pipes that exited in front of the rear tires, That car ran 12.23 at 109.4 MPH through that exhaust, it ran 11.39 at 117.7 MPH with it removed
The next pump gas street race car I built had a 3.0 exhaust system on it from the same h
Hooker headers off of the Dart to a set of rear mounted(behind the rear end) Magnaflow oval 14x3.0x7 inch long muffs with no tips or tail pipes(they where mounted at the rear bumper )
That car ran 7.01 ET at 95.4 MPH with that exhaust system on the car and ran 6.98 at 95.6 MPH with it off
I would and do use three inch now for any of my half way serious street cars
My next street racer will have 3.5 or 4.0 inch on it

PS Cab is deaf

3 inch all the way out the rear with a good set of mufflers is what I would do. Key is to run tailpipes and not dump it under the car, or out the sides right below your ears.

So, I take it this is pretty stock with 400 hp? Really a stock system would be fine.But a 2 1/5 would be all you will need with an H pipe.I have a 528 with a 2 1/5 stock system with resonators, and it is good enough for the street. The mufflers are Hemi mufflers that flow better than stock.

Have you ever ran your car without the current system with no other changes?
The reason I ask is that I didn't "feel" the .9 ET and 8 MPH increase in my old Dart by removing the exhaust system and I have a ton of time in race cars
That car weighed around 3500 Lbs. with me in it so do the Google on how much HP that old stock stroke stock bore 440 motor made, it was not a rocket ship even back then

3" (with mandrel bends) from end to end would give the highest nth degree of performance but would need creative work to keep it down to a loud roar. Dyna max Hemi muffs up front & glasspacks alongside the rear leafs & maybe helmholts resonators or other tricks. My take: a very quiet restricted system & cable (preferred) or vacuum cutouts right at the collectors so I can TOTALLY control the noise factor, I ain't in high school & when the money is in the hands of a neutral 3rd party then I can let er rip & 10 seconds later the money will be in MY hands.

I took it as a street car with an almost stock, or stock engine. Without dyno time, who knows what the power level is. He didn't say headers, or not. I just remember back in the day how good a big wedge sounded with a stock H pipe system. You can cruise for hours without the noise, but step on it, and then you could hear it. The bigger everything is the harder it is to hide, so I thought 2 1/2 would be big enough for a stock street car.

2 1/2 is fine for a street car.

Cab is in the narrow mindset of "everyone is a drag racer and every question is drag racing related, money is no object" group.

Not exactly, my mind set is do it right once and don't look back
My intent for my half way serious street cars is to be able to show most other hot rodders my taillights when needed

Your fine with what you have, don't fall victim to the "size matters" crowd when it comes to exhaust systems, if you were pushing 1000 Hp, then yes, but with your combo, your more than adequate, unless your mufflers are very restrictive? what type/brand mufflers are you running?

Dynomax Ultra Flow Welded