[Mexirican]

I am torn here. I know that a 2.5" exhaust is good until 500hp or so but what is the flow difference between a 2.5" system with x-pipe and a 3" system without an x-pipe. I'm putting this system on a '72 with a 450hp 383 (600hp 406 in the works) but I only want to do the system once. It's a drag car that can be driven on the street. Also, I’m not putting tail pipes on. I plan on having the exhaust dump right after the muffler.

Thanks for the help.

 

[sbc1320]

I run a full 3" with Pype's x-pipe on my 383 which should go over 500 hp.

With your new 600 hp build I would definitely put the 3" system.

Here is a picture of mine:

 

[Mexirican]

What mufflers are you running? I have a set of 2.5" Flowmaster 40 series already. The husband of a lady I work with runs an exhaust shop and does pretty awesome work. He said he sells those mufflers all the time and since mine have never been installed and are still in the original box, he'll buys them from me at retail and credit me for whatever I want to get in its place. I've heard that the 40 series doesn’t flow as well as others out there but I love the sound, especially with a 3" system.

 

[Rich74custom]

I ran 3" 40 series flows and 44 series, both flow great. anyone saying they dont, havent really had them. The sounds are a little different. I like the 40 series the most. I switched to 2.5" with an x-pipe and large body magnaflows to keep it quiet. Now its to quiet. :bored:

 

[sbc1320]

What mufflers are you running? I have a set of 2.5" Flowmaster 40 series already. The husband of a lady I work with runs an exhaust shop and does pretty awesome work. He said he sells those mufflers all the time and since mine have never been installed and are still in the original box, he'll buys them from me at retail and credit me for whatever I want to get in its place. I've heard that the 40 series doesn’t flow as well as others out there but I love the sound, especially with a 3" system.

I am running the Super 44's and tailpipes. A buddy with the same exact setup minus tailpipes(he isn't running any) has this system on his 72, but his isn't as loud as mine. I have more compression and cam than his engine has.

 

[sbc1320]

That x pipe is the universal one from Pypes and is stainless steel. Front bell cut off to fit into my Dynatech collector extensions and about an 1" cutoff off the tail end of the x pipe pipes. Fits the car perfect and no other piping needed as long as you have the long collector extensions that came with my headers( 1 3/4" x 1 7/8" stepped).

 

[friskiersaucer]

An x-pipe is not going to compensate for smaller pipe. It will allow the exhaust to scavenge more (pulls exhaust out). 450 hp is fine 2.5 but if you get around 600 hp your defiantly going to want to go with 3"

I have 40 series flowmasters and love them!