jt76

iTrader: (10)

I have been trying to decide on what i want to do for an exhaust on my car. I have a twin kit with two 3" downpipes coming down the passenger side and both pipes end about halfway back on the t-56.

Originally, i was going to do 2 electric cutouts and then merge them into my 3" Borla catback. This seems like a lot of farting around and my friend suggested that i simply merge both 3" pipes into a 4" and build a custom 4" exhaust out the back of the car.

What do you guys think? Will two 3" pipes merged into a 4" and routed through a muffler (bullet style or chambered?) cause a significant loss of power?

car is a forged 6.0L with twin pt6262's I will be running 17-18psi turned up.

thanks.

I8UR4RD

iTrader: (16)

bull horn it man! who doesn't love flames shooting out the side of their car. All the more reason to call it a Fire Bird.

jt76

iTrader: (10)

LOL

I want to make MORE civilized!

2000RATA

I have custom dual 3" aluminum with magnaflow mufflers ran all the way out the stock openings. If your talking about making it custom you might as well go duals. I had mine back at the dyno with this exhaust (previous dyno was open pipes) and was making 904 rwhp at 13 psi and the clutch started slipping. It previously made 945 at 14 psi with open down pipes but the clutch wouldn't hold more than this. I have replaced the clutch since but haven't been back yet. No doubt it will do 1000 rwhp easy. Not to mention it sounds way better than a single setup.

jt76

iTrader: (10)

I don't really want to do duals all the way back due to available space and cost of 2x the materials.

Reject

iTrader: (24)

why not merge it like your saying with the 4 and add the cutout inline there? that way you have the best of both worlds.


and i agree with the cost of material becoming insane when running duels

Cam72aro

iTrader: (28)

Do the mufflex catback. Merge them into it

willizm

iTrader: (10)

I'd say if you decide to merge it down to a single 4" just wire up electric cutouts on the 3" dp's. yes you will lose hp with a catback but when you are pushing the car you'll probably have the cutouts open. I love my cutout. I use that thing damn near every time I drive

jt76

iTrader: (10)

will the initial necking down to 4" hurt anything or will the difference be negligible with the cutout open?

jjcamaro02

iTrader: (34)

I am running 3" pipe off headers to a 3" to 4" Flowmaster y-pipe. Single all the way back to a Magnaflow 4" race muffler. You don't need a cut out many guys running deep in the 8's with 3.5" and 4" single. I believe MIGHTYMOUSE was running 3.5".

itsslow98

iTrader: (18)

Your definetly gonna have the best performance with two 3" cutouts. After that I would focus on whatever you want it to sound like and just open the cutotus when you wanna beat on it. I have a cutout by my trans and then I just ran 3" back to a magnaflow straigfht through and dumped it and the car is so quiet you can barely hear it at idle. I usually just run with the cutout open all the time but its nice to have a silent car for long highway cruises.

jt76

iTrader: (10)

Yeah, i def want it quiet while cruising. Right now it sounds like a boat and drones like a **** with it dumped pretty much right under the passenger's feet.

jt76

iTrader: (10)

bump, any more input? I would like to do this before the snow flies at my buddy's shop.

Forcefed86

iTrader: (4)

I'd run the cutouts, and a quick and dirty crush bent 2.5" system out the back with a large chambered muffler. Would give you stock like noise levels with the dumps closed. Easy to route 2.5 crushbent piping as well. If you run dumps what is the point of having a "performance" 3"+ exhaust system going all the way back?

I have my 4" down pipe necked down to a 2.5" glass pack for cruising. It's freaky quiet. Then I have a boost activated dump. I see 1-2 psi of back pressure in the exhaust system with the dump closed cruising and lite load.

Could also merge both turbos into a 4" Y with one dump. Then "T" off that to a 2.5" system out the back.

Here is a good example... 5" exhaust to dump, then tiny pipe to the rear.





I always had trouble with my electric cutouts. Boost activated cutouts are the way to go IMO.

jt76

iTrader: (10)

Where did you get that boost activated cutout? That is pretty neat. I've never heard of one.

68 SS

iTrader: (23)

The boost activated cut out is a cool idea a little expensive though http://www.spracingonline.com/store/

jt76

iTrader: (10)

$400 per, ouch. Also says it is not fully opened until 17psi.

willizm

iTrader: (10)

Primarily used in the Supra world. I'm sure if you call those guys and ask for it to open at 6psi they could probably build you something. Ask for Reid. My only concern with an ecutout is the time it takes to open.

Forcefed86

iTrader: (4)

$269 here with the "T" pipe and clamp. (Available in 3") I believe I had read these open fully at 10psi. It's just a WG actuator. You can buy gates that open more quickly cheap on ebay. Or open up the gate and change out the spring.

http://www.himni-racing.com/index.ph...1dpbfebe4gnlu1

smokeshow

iTrader: (17)

I had dual 2.5" downpipes into a single 4" and the setup made more power than I needed. Truck weighed almost 5000lbs and pulled 130mph cobras without too much trouble Both options will work. The exhaust sound will be the biggest difference.