i can get 1 3/4 headers made,,no problem,,,,will duel 2.5inch be torque robbing ,,,,ie;too much,,,,,or will a single 3 inch be better,,,,low end torque,,,either way here its a full custom system due to the steering being right hand drive,,,both systems are aroung $2500,,,,,,

 

I would stick with a single 3" exhaust. Seems like the fab work will be high to run two pipes instead of one. Neither will rob power and you should feel the same performance out of either. Theoretically dual 2.5" will outflow a single 3" but that is when you are making over 450hp to the wheels and 3" will not suffice.

 

When you calculate the area of the dual pipes it works out to be 4.906" each or a total of 9.812" inside area. A single 3 inch pipe is 7.065" of area. The dual 2 1/2" pipes most likely will not be mandrel bent, and therefore the area will be reduced at certain points. It has been proven by other members that you can go fast with a good single 3" system. Traxion is running 11.6's with 3" single, I ran 12.40 when I broke a roller lifter, and I have single 3". I don't believe that you would lose any noticeable torque by running the duals because when you factor in all of the variables, i.e. non-mandrel bends, two mufflers, etc.., your exhaust will not flow a ton more than a good mandrel 3" system.

 

It has also been shown that a modified engine (not a stock L98) can go a lot faster with a better exhaust than single 3". I swapped from single 3" to dual 2 1/2" with an X pipe and there was a definate difference. Someone with a 383 recently posted that he swapped from single 3" exhaust to a cutout and picked up a half second in the 1/8th mile...

 

huh?

Tim

 

Well considering that he has a 409cid motor, i would have suggested the 4" system from mufflex which has an area 12.56" which is technically superior to dual 2 1/2", especially if it's not mandrel bent. The problem is that he didn't mention what headers he was going to run, outside of the fact he could get custom 1 3/4" tubes. If he's going to run shorties with a high flow y-pipe, it will be a 3" collector, most likely. It will not make much difference to to have more than a 3" system, if the y-pipe and collector is 3". The best method would be open headers or cutouts, as they will be LESS RESTRICTIVE than any other exhaust system, although not necessarily the highest flowing, but open headers are not practical for everyone. I was not saying that "I have 3", and so do some other people, so you should run that too." I was simply stating that single 3" flows well enough for most vehicles. It comes down to how much can the muffler flow. Two mufflers on a true dual, that flow 500 cfm each, will be half as restrictive as a single 500 cfm muffler system. a single muffler that can flow 1000 cfm will be as free flowing as a dual 500 cfm setup. By the way, how many mandrel bent true duals for third gens, have you seen? Those standard bends are pretty restrictive. Ultimately, we all do whatever we feel is practical, beneficial, or desireable.

 

my true dual system on my old camaro was totaly manderal bent (to include the dumps infrontof the rearend) the only bad thing about my system was ground clearance.

 

here is a pic with it on the ground.

 

mandrel bent x-tensions.