Exhaust system mods - need advice
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Exhaust system mods - need advice
I have a pair of EXHD12 shorty headers on the way for my 289 1967 coupe.I would like to replace the old H pipe with one of the new "siamese" designs- I understand this will quiet things down and buy a couple HP. I'm looking seriously at the Summit SUM-642125 Kit, as it's the lowest cost on the market. The headers have a 2 1/2 inch collector flange, and the Summit kit is also 2.5. My muffler system is 2 inch all the way, and I would like to keep it from the mufflers back (it's almost new). I really don't care if it has a little back pressure, since I'm under 300HP. I have two questions:
1) Where would the best place be to do the reduction from 2 1/2 down to 2 inches. Before or after the X? If after the X, then where it leaves the X or at the input to the muffler? My guess would be at the muffler inlet, since this would present the smallest length of "small diameter" to the system, and allow more opportunity for the gasses to expand and cool before hitting the muffler. I'm hoping the 2 1/2 inch pipe will also help to quiet some of the resonance around 2000 RPM. I'm running Magnaflow mufflers. They sound very nice - almost sound stock at cruise and definitely "speak up" when the secondaries are open. Just a bit of resonance between 40 and 50 MPH.
2) Where is the best place to put the X? Closer to the headers or closer to the mufflers, or does it not matter?
3) Where do I find some 2 1/2 inch pipe to mate up the header collector flange to the front side of the summit kit? Is this something the local muffler shop would have or could fab for me?
4) I hate to see all those clamps - they seem like opportunities to leak. Would it be wise to weld up at least the 4 connections to the X pipe section? Same question for the collector/pipe joint...
5) What's the best do-it-yourself High temp paint for the headers? I don't want the expense of ceramic coating -even though I know the benefits. Trying to keep the bucks low, but still put something on the headers that lasts. Should I sand them down and remove whatever comes from the factory?
If anyone has photos of a setup like this, please post them so I can see how you did it.
Thanks!
1) Where would the best place be to do the reduction from 2 1/2 down to 2 inches. Before or after the X? If after the X, then where it leaves the X or at the input to the muffler? My guess would be at the muffler inlet, since this would present the smallest length of "small diameter" to the system, and allow more opportunity for the gasses to expand and cool before hitting the muffler. I'm hoping the 2 1/2 inch pipe will also help to quiet some of the resonance around 2000 RPM. I'm running Magnaflow mufflers. They sound very nice - almost sound stock at cruise and definitely "speak up" when the secondaries are open. Just a bit of resonance between 40 and 50 MPH.
2) Where is the best place to put the X? Closer to the headers or closer to the mufflers, or does it not matter?
3) Where do I find some 2 1/2 inch pipe to mate up the header collector flange to the front side of the summit kit? Is this something the local muffler shop would have or could fab for me?
4) I hate to see all those clamps - they seem like opportunities to leak. Would it be wise to weld up at least the 4 connections to the X pipe section? Same question for the collector/pipe joint...
5) What's the best do-it-yourself High temp paint for the headers? I don't want the expense of ceramic coating -even though I know the benefits. Trying to keep the bucks low, but still put something on the headers that lasts. Should I sand them down and remove whatever comes from the factory?
If anyone has photos of a setup like this, please post them so I can see how you did it.
Thanks!
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AMAlexLazarus
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Apr 4, 2020 02:16 PM
