I'm deciding on my new build, supercharged 350 putting well over 400 out, but the engine shop told me i should do true duals to get the most out of it, but he said i still have the option to do ypipe. I don't mind either of them, i just want ot make sure which will give me the best backpressure and least restriction while still making maximum cleareance as stock or better...

need some opinions and results of people who have already done this. No there wont be cats after the year mark on the vehicle. Deciding still if i even want a muffler, if so any good options?

 

My opinion will always be that a properly designed y pipe is better than duals. You might make marginally better power with duals but its not worth the sound, nor the ground clearance.

 

Either will work. Just size correctly and then it's up to personal preference. You can get pretty involved with header/exhaust design but here are two good rule of thumbs:

1. For avoiding significant restriction from back pressure, the pipe should flow at least 2.2CFM per horsepower produced.

2. A straight pipe will flow ~115CFM per square inch of area (using inside diameter of the pipe)

Using these, a 500 HP engine will need at least a 3.5" single system or 2.5" dual system. Benefit of single system is that you can by bolt in catback kits like the 3.5" or 4" mufflex systems. For single need to make sure muffler flows enough or you could always look into a race style muffler. Since you won't have cats, will need to buy or fab small connector piece from exhaust to headers. For duals it's easier to find a shop and have them make it. You can run dual 2-1/2" pipes in stock position and snake them over rear axle (I have this). Would be good idea to add in a x-pipe.

Do you have aftermarket headers? Good shorties like Hooker 2055 or Dyno Don's will work for your power level and install easily. If you are going through trouble of redoing exhaust long tubes might be worth it. May have fitment issues with them and ground clearance will be low. Is your transmission and rear end upgraded? Will need to with that much power. Sounds like it will be a nice engine when completed.


http://www.mufflex-performance.com/fbody_2.html

 

Since "true duals" (1 pipe per side) is going to be illegal, that pretty muchg settles it on a street car.

Besides, there isn't really much room under the drivers side for pipes anyways, without compromisiing ground clearance issues.

 

why are true duals illegal?

 

The cats can't even be moved. They have to stay where they are.

 

if you have cats on the exhaust and you pass the sniffer, 9 outta 10 inspection shops wont care. stephen is right though, it is technically illegal

 

You're not allowed to alter locations of stock emissions equipment. Since you are going from 305 to 350, I think that may qualify too. Not sure what CT does for emissions? Visual inspection or sniffer only? Certain states exempt cars from emissions after a time period.

 

I love living Free..not having to get the car looked at..Ever!!
never having to go and get a OK to get tabs..lol

no checks..no Cat's...

just good old long tube Headers.. Cutout's and out the back..

just good old free flowing hot rod Fun!!!

 

thats why i said 5 years from now.. that makes the 25 yr mark where the vehicle doesn't go through inspections anymore or emissions.

 

FYI......Lack of emissions testing doesn't mean everything can be legally ripped out. It only means no more TESTS. VISUALLY, the car can still fail inspection.

 

yeah it may be illegal, but so what. duals all the way.

 

If pulled over by a cop, correct? if not then, it shouldn't matter since the vehicle doesn't have to be ran for cat inspection after 25 either.

 

honestly cops won't even check unless you really **** them off.

 

Incorrect. Pull ANY of the emissions stuff off & the Inspection Ststion can fail the car based purely on visual.

 

After 25 years the car doesn't have to be brougth for inspections.

 

Really? Must be a CT thing. Only way to avoid inspections in Texas, is to register it as an Antique Vehicle, which limits how much you can drive & when you can drive it.

 

must be... because i read the dmv and emissions, you could even register as a antique and drive it 200k miles a year with no problems.

20 years its a antique in ct, then 25 years theres no more emissions that the car has to go for. No inspections or anything. Also in ct after 25 years you may even change the color of the vehicle and engine and it doesn't have the be documented that its been changed, you can even claim it came with it, and its fine. just within the 25 year period it has to be as it is stock, you can do bolt ons and other things, just as long as it passes emissions its fine.

 

In wisconsin there are no emission testing on 20 year old cars. Recently my county stopped testing all obd1 cars as well. This after my car failed 9 times on its 19th summer. I finally got it to pass. btw even when I was basically living at the dmv they never bothered to look at anything on my car. My custom long tubes or the fact that the cat was moved from the stock locaton. They were only worried about if it passed the im240 test. Fyi don't make blanket statements about what is required everywhere. Alot of states have different requirements. When getting pulled over, if you turn off your car before the officer gets out of his car, there is a much smaller chance that he will inspect your exhaust system.
Just my .02
Kory

 

It's nice not to have to Put Up with anything like that..

it's bad enof i have to pay a $200 tax stamp on every full auto weapon i Buy.. and another on every suppresser i buy.. big brother LOL

But my Hot Rod is ok...

 

In California car built from 1975 to present must retain all smog equiptment and will have to be smog.

Oh by the way, up to 5hp is the difference between true duals and single exhaust. On the southern cali board we have people making from 360hp-403rwhp with single exhaust systems with dual cats and all the smog equiptment hook up. Can you prove that you will loose over 5hp with the smog hook up?

 

can you prove you can make 600hp with all the smog Junk.

in washinton we have cars running on the streets that Cut 9sec 1/4 mile times and look stock from 20 feet away...

and we can buy suppressers... (cant use them)...lol
But we all do..

 

Some of the ls1 cars are 600hp with the smog junk still on it with Superchargers. A lot of Supercharged mudsatangs are 600hp with the smog junk still on them. It's all about how you build it.

Question? How much hp is really lost with the smog junk? If you tune the car to pass smog you will get the best MPG.

 

it's all about no having stuff on the car.. that you dont have to have.
some states.. you can get away with not keeping it..

make room... drop a few LBS..git rid of it...thats what I say..LOL

I DID the Lingenfelter thing and after time got rid of the smog stuff and was faster..But thats me.

 

All that is good if you're racing the car but for a daily driver what is the purpose? If the car is making less than 350hp for the amount of parts installed on the car, what are you trying to accomplish?