PhoneniX

I am planning my exhaust mods for next year. With these Goals: 1. eliminate rasp 2. clean up foul odor (raw exhaust smell in traffic) 3. gain some power on retune.
Current setup: 224/228 .588/ .591 110lsa comp cam+ supporting internal mods, Hooker LT's, Doug's ORY, Magnaflow muffler.

I am unhappy with the Doug's headers y-pipe as can be seen on summit. I also pre-purchased highflow spun magnaflow cats pn: 59959 to install in the Y-pipe. The muffler shop won't touch it so I am left to do this myself. I am a week into researching this and have drawn some conclusions, however I am driven by facts not anecdotal evidence.

I plan on using the doug's Y front section and hacking in a proper y-pipe collector. I have read about the "Pat G y-pipe" using the flowmaster 3 inch in to 4 inch outlet merger. But I have found magnaflow pn: 10798 3 inch all around merger which would fit directly with my 3 inch converters *have not found a 3"in and 3.5 or 4in outlet yet. Does it exist?

After a forum search I have not found a comparison of the magnaflow style merger to the Flowmaster, and with the current premium that the flowmaster charges ($50 Flowmaster vs. $30 magnaflow) I am curious to hear facts. I understand It is hard to compare a 3 inch in/out merge to a 3 inch in to 3.5 inch out (or 4 inch as recommended), but at this time I do not see magnaflow with the same setup. I appreciate how the magnaflow is stainless vs. flowmaster being aluminized and in my case the 3 inch square setup means no reducer required for my converter install.

Question section:

• Other than outlet size difference is the overall design shape of either better at neutralizing rasp?
• Is a manual cutout before the catalytic converter worth the hassle in a Daily driver?
• *side note: I have been convinced that one highflow spun converter after the y-pipe merger is safe and will not plug with a proper tune. Any fact/ experience with a converter this far back getting up to operating temperature?

Considering this pipe selection:
Hooker LT's >
Doug's Y front section >
Magnaflow 10798 merger >
1 Magnaflow 59959 catalytic converter >
and keep stock I pipe to magnaflow 12267 muffler >
Dual SLP tips.

Or

Hooker LT's >
Doug's Y front section >
Flowmaster 3" in 4" out >
Unknown 4" manual exhaust cutout >
4" to 3" reducer >
1 Magnaflow 59959 catalytic converter >
and keep stock I pipe to magnaflow 12267 muffler >
Dual SLP tips.

Please help convince me oh great Ls1tech members

PhoneniX

Some good pics of the Magnaflow 10798 merger piece are found in this thread: https://ls1tech.com/forums/generatio...ge-review.html

While for mathmatical pipe area see: From: https://ls1tech.com/forums/generatio...er-y-pipe.html

Corvet786c claims big hp with the 4" collector, IMO the gain seems to be the 4 in intermediate pipe as in my setup I will be bottlenecking to the 2.75 inch Intermediate pipe before the axle in either case. I purposely put power as my third goal, I was dynojet tested with 355rwhp after a quick n dirty tune on cam. I hope to reach the expected 380hp after a clean tune on this exhaust and a ls6 intake swap. Proof of 2.75 in supporting this hp would be this 500hp on 3 inch pipe claim

HCI2000SS

iTrader: (2)

All I can tell you is that the FM merge did a very good job in eliminating my rasp

01ssreda4

iTrader: (96)

I have the magnaflow merge on my yukon, and even with manifolds and cats it has rasp (buddys does too, I built him the same exhaust) and I put a flowmaster 3 to 4 on the camaro with a bullet and it has no rasp. Flowmaster flows the gases together a little smoother I think so maybe thats it....

Hamrdown

iTrader: (25)

I actually have the pic saved on my phone of Pat G's y-pipe.


I don't think Flowmaster carries this style merge anymore. I've used their newest version and I must say that I like the design a lot better than Magnaflow's. The cats will definitely help with the unburnt fuel smell and will help some with the rasp. Though the new y-merge will help more than anything in that dept.

PhoneniX

I think i've convinced myself that the flowmaster y-pipe with a 3in inlet and 4in outlet is the way to go. However as for the cutout I am having a hard time justifying the additional complications and possible future leaks. If I can get a local friends help I am going to look into fabbing up a 3" I pipe to the muffler again off the cat. Probably using cut up mandrel bends from summit because I already have to buy some pipe to correct the y-pipe into the collector..

Is any feedback on manual cutouts guys?
I think its a go big or go home topic on cutouts. Manual removal seems so impractical and electric cutouts have me questioning longevity.

01ssreda4

iTrader: (96)

My 4" QTP was rock solid. I loved that thing. Never rattled or leaked. Would not hesitate to buy another one.

PhoneniX

The owner of a 5.7l dodge challenger showed off her electric cutout at a local car show today. I have to say I was impressed with the exhaust, as I did not value the fact that the butterfly valve can be opened at varying degrees before. But man what a difference between fully open and partially open. Looks like that may have sold me on it, time to start saving.

01ssreda4

iTrader: (96)

Partial open always jus sounded like a big *** exhaust leak to me. Nothing apealling about that.