Please help me plan exhuast system

[sauldgold]

Hi everyone,

I have just rebuilt the engine on my daily driver: edelbrock e-tec heads, lunati cam (211/219 @.05) and jba shortys

my goals for the exhaust are as follows:

1. performance
2. no drone
3. nice mellow rumble at idle
4. strong sound at wot, but not necessarily as loud as possible

Toward that end, I'm leaning toward a catback Magnaflow 2 in/2 out

What I would like to know is; is the stock 2" diameter mid pipe sufficient for my application or would I now require 2.5" pipe because of the engine mods?

 

[SunlitComet]

think it was 2.25 actually going from manifolds all the way to the muffler and 3 inches output. yous would keep it the same size but the crossover pipe,converter assembly will be a sticking point. Might i suggest you get a whole new converter assembly from magnaflow or similar that uses mandrel bent tubing all around. as for the cat-back i think you will have drone no matter what. some are quites then others but i don't think you can avoid it completely without effecting performance.

 

[sauldgold]

Thank you for your quick response.

Regarding the stock mid pipe/cats being a 'sticking point' -- how significant do you think it is?

Secondly, there is a real price discrepancy between Magnaflow's CA approved mid pipe/cats and their 49 state model -- are there any actual engineering differences between the two, or is it simply a matter of the company charging a premium for having gone through the trouble of the approval process?

 

[ezdaar]

Thank you for your quick response.

Regarding the stock mid pipe/cats being a 'sticking point' -- how significant do you think it is?

Secondly, there is a real price discrepancy between Magnaflow's CA approved mid pipe/cats and their 49 state model -- are there any actual engineering differences between the two, or is it simply a matter of the company charging a premium for having gone through the trouble of the approval process?

Buy the 49, tell cali, F off.

 

[sauldgold]

I tell them that everyday, but they don't seem to listen

 

[SunlitComet]

cali converts use more precious metals and require more research work, testing and certification work to meet cali standards. that raises the cost. we just get better converters here and with a longer warranty then federal ones. as for the crossover pipe any bend on it that is not mandrel creates restrictions for it to overcome. Now that does not mean you can't get a shop to make just the crossover pipe. as long as components stay in same location you should be just fine anyway you do it. if you do install new converters put new sensors on them as well so they are treated and monitor well by the pcm.
when my set up was complete i had doug thorley tri-y's headers with magnaflow cats and flowmaster cat-back that included a 50 -series on it. the crossover pipe to converters was part of the header kit.

 

[sauldgold]

Thanks guys, this has been a huge help.

One last question, is there any sort of consensus on the life expectancy of the stock cats?

 

[SunlitComet]

my original went past 240k+ i popped a efficiency code maybe twice in a year before replacement. Primarily tho they were replaced as a new entire exhaust system was being undertaking.

 

[sauldgold]

Ok.

I have settled on a Magnaflow 2 in/2out muffler -- which I figured I would simply have welded to my existing 2.25" pipes, however many of the prefab cat back systems are using 2.5" intermediate pipe and at least a few posts here suggested using 3" intermediate pipe...

What do you advise?

 

[ezdaar]

Do not go smaller than your current pipes.

With your mods. go with 2.5" duel with a X pipe.
Or the high flow magnaflow cats and y pipe to a 3" catback.

But. The way it should really be done.. Long tube headers with no cats, and one of the options above.