BBC exhaust options

[pismorat]

I am putting a big block in my truck and am wanting to know my exhaust options. I currently have a smallblock with single 3" exhaust and a Flowmaster 2-chamber. I want it loud, but would like to stay away from dual exhaust. The big block has Thorely full length headers with 2.5" collectors, so I wanted to run dual pipes to a single Flowmaster with dual 2.5" inlet/dual 2.5" outlet and use turndowns. Would this provide enough flow?

 

[pismorat]

Nobody?? The basic question is will a dual in/dual out Super 40 create too much back-pressure or will it be sufficient?

 

[folkenheath]

I have a dual inlet/outlet Flowmaster in my Regal (Flowmaster GN system), but it's hooked to dual 2 1/4" pipe from headers back. It's a ~425 hp 388 SBC. If I uncork it it drops 2 tenths from my ET, which is ~20 hp at the wheels. To be honest that's not as bad as I thought it would be, but my single muffler is all the way in the back, behind the axle, with only 2 ft of tailpipes. The farther forward the restriction is the worse it will be. Hope this gives you an idea of the performance.

 

[76zimmer]

I am putting a big block in my truck and am wanting to know my exhaust options. I currently have a smallblock with single 3" exhaust and a Flowmaster 2-chamber. I want it loud, but would like to stay away from dual exhaust. The big block has Thorely full length headers with 2.5" collectors, so I wanted to run dual pipes to a single Flowmaster with dual 2.5" inlet/dual 2.5" outlet and use turndowns. Would this provide enough flow?

Post up a pic of those headers in the vehicle would ya?
I'm trying to figure out what I want to run on mine.

Thanks.

 

[454 blazer]

Ive been running a big block now for 3 years with the 2nos 2 chamber flow masters they are very loud when you wind it up and they have an awsome rumble on tick over if you have a nice cam.Check some old vids i have on youtube type in 454 blazer its the white one with blue stripes.Hope this helps.Also good luck putting the big block in your blazer,its well worth it !

 

[4X4HIGH]

I am putting a big block in my truck and am wanting to know my exhaust options. I currently have a smallblock with single 3" exhaust and a Flowmaster 2-chamber. I want it loud, but would like to stay away from dual exhaust. The big block has Thorely full length headers with 2.5" collectors, so I wanted to run dual pipes to a single Flowmaster with dual 2.5" inlet/dual 2.5" outlet and use turndowns. Would this provide enough flow?

First let me ask you this, does this vehicle have to pass emissions testing here in California? The reason i ask is because of the new law that passed January of 2009 regarding Catalytic convertors and exhaust systems.

 

[pismorat]

No on the SMOG, it is exempt

 

[Cornfield creations]

A dual in-dual out super 40 should be enough. It might not have the volume at higher RPM's, but being a 5 inch shell vs. a 4inch it helps. Working at an exhaust shop we're not to fond of the flowmaster's, neither are the suppliers. They do ok, but when it comes to flow and sound it's hard to be magnaflow. They make a dual in dual out if you like. I would stick with a 5x8 oval part # 12468, that also has a tru-x core in it. If you want it louder they make a 4x9x14 part #11386, it also has a tru-x core. If you're worried about flow, go with magnaflow. If you want just a specific sound like flowmaster, then stick with flowmaster.