exhaust opinions

[sneakyfast]

Ok gents I have a 73 with a 383 stroker that the Po has a 3 inch running that dumps right behind the cab and is loud enough to rattle your fillings lose. I'm considering running 2.5 if it doesn't kill my power. Its a daily driver so

1. Will I notice a power rob? Ive seen some opinions say I shouldn't notice a difference until the motor is running 500hp but that doesn't sound right
2. The Po also is running full length headers, should I change these to shorties at the same time or does it make no difference?
3. I used to love the sound of flowmasters but they have a bewildering number of choices in 2.5 inch. Any recommendations?
4. He has a 950 cfm crab which seems huge to me but will I need to change that out to?

Thanks guys and when you reply lets pretend I was raised in a public school and have been out of cars for many years

[piecesparts]

When I built my first 383 stroker engine for my 84 GMC, I spent some time talking to different exhaust system manufacturers and system dealers. This is not the local pipe benders, but the guys that make and sell Flowmaster and Magnaflow systems. I came to one common thing from all of them, there is such a thing as too much on exhaust. I am now on a second stroker engine, due to throwing a rod out of the first one at well over the measured 80 MPH on the speedo. It was our fault for using that brand of rods, not something else going wrong.

The systems have to be large enough to flow easily, but small enough to allow for the exhaust fumes to cool efficiently and create a negative pressure effect to help remove the gasses from the cylinders. Otherwise you could have a lazy exhaust flow and cause yourself more pain than gain. For my SWB truck a set of 2 1/2" dual exhaust pipes from my headers would provide the most optimum flow and not cause any reversionary effects.

I have a set of headers with 3" collectors that go to dual 2 1/2" pipes going back to an "H" pipe crossover and then into two Magnaflow stainless mufflers and then into pipes that are 2 1/2" pipes to the rear roll pan. I used to run Flowmaster but after having to replace the mufflers twice for rusting out, I went to the Magnaflow stainless mufflers.

According to most of the techs at the manufacturers, the 3" exhaust system would work great for a really large engine with a lot of assistance on the air intake, to make it work properly. Your street driven truck with a SBC will work very well with the 2 1/2" piping.

[andrewmp6]

Unless your dragging the headers i would keep them on it,A full length header flows better then a shorty header.

[sneakyfast]

Originally Posted by piecesparts

When I built my first 383 stroker engine for my 84 GMC, I spent some time talking to different exhaust system manufacturers and system dealers. This is not the local pipe benders, but the guys that make and sell Flowmaster and Magnaflow systems. I came to one common thing from all of them, there is such a thing as too much on exhaust. I am now on a second stroker engine, due to throwing a rod out of the first one at well over the measured 80 MPH on the speedo. It was our fault for using that brand of rods, not something else going wrong.

The systems have to be large enough to flow easily, but small enough to allow for the exhaust fumes to cool efficiently and create a negative pressure effect to help remove the gasses from the cylinders. Otherwise you could have a lazy exhaust flow and cause yourself more pain than gain. For my SWB truck a set of 2 1/2" dual exhaust pipes from my headers would provide the most optimum flow and not cause any reversionary effects.

I have a set of headers with 3" collectors that go to dual 2 1/2" pipes going back to an "H" pipe crossover and then into two Magnaflow stainless mufflers and then into pipes that are 2 1/2" pipes to the rear roll pan. I used to run Flowmaster but after having to replace the mufflers twice for rusting out, I went to the Magnaflow stainless mufflers.

According to most of the techs at the manufacturers, the 3" exhaust system would work great for a really large engine with a lot of assistance on the air intake, to make it work properly. Your street driven truck with a SBC will work very well with the 2 1/2" piping.

Thanks for the reply and any thoughts on where to run the pipe? I thought about exiting behind the rear wheel or maybe pointed down before the end of the bed as I'm not to crazy about the looks of pointing out the back of the bed

[piecesparts]

Originally Posted by sneakyfast

Thanks for the reply and any thoughts on where to run the pipe? I thought about exiting behind the rear wheel or maybe pointed down before the end of the bed as I'm not to crazy about the looks of pointing out the back of the bed

If you exit on the sides behind the rear tires, you will still get some noise feedback to the cab. If you turn down anywhere under the bed, there is also sound feedback to the cab, not to mention the one thing that I hate the most. The exhaust does nothing but stir up dust a garbage off of the ground when you drive. I take mine to the rear and then I use a MEGS stainless oval tip from Cone engineering to make the exhaust blend in with the bumper. It's just me, but that's my point of view.
Attached is a picture of my old 91 Silverado, but I also have my 2011 GMC set up this way.

[motornut]

Yes my Jimmy with turn downs under the cab,
creates a cloud of dirt behind me,on rough/dirt/snowy roads...
not good for a nice paint job,but sounds good to me lol

[piecesparts]

Every guy for his own. Remember it is not just your paint job that you are blowing dirt up on. Nothing like being clean and shiny and someone going by and dusting it up for you.