I'm trying to reduce/eliminate my ARH y-pipe from intermittent rattling against my aftermarket torque arm brace. We installed new OEM engine mounts in 2019 when the engine was built. My aftermarket torque arm design has a cross brace which has already been lowered about a 1/4" at the behest of the engineer that designed the TA, so no further spacing due to geometry and ideally remove both 1/4" spacers. With the latest exhaust shop adjustments this morning, the y-pipe clears that brace by about a 1/2" with the engine off.

My y-pipe randomly knocks only against that brace, no witness marks against the chassis from the exhaust anywhere else. The exhaust shop is basically out of ideas due to tight brace clearance and how much the y-pipe is vibrating from the engine vs other tradeoffs.We did replace the rear OEM hangers with stiffer hangers and they don't think I could raise the tips too much without the over-axle pipe hitting the chassis. They did recommend a Magnaflow muffler to replace the SLP dual/dual muffler to reduce resonance, as it sounds as if the internal design has been compromised, possibly related to removing the cats in 2019. I've heard the Corsa exhaust design is good at reducing resonance, and I've also seen the posts that show additional tubes welded on to reduce resonance. I'm not interested in adding significant weight, nor using an upper panhard brace that is not 100% straight.

Our current ideas are below, any other suggestions?
- Reduce over- and underspeed timing tables that may reduce the engine vibration at idle
- Replace the 12 year old ATI Superdamper since ATI recommends rebuilding it at least every 10 years. Perhaps it will reduce some of the engine shaking.
- I'm considering new primaries with a Y-pipe, perhaps ARH could provide a modified y-pipe that is a flat oval for additional clearance. Exhaust shop says I wouldn't have enough clearance for a 3.5" y-pipe outlet.
- If the headers are being swapped, it's a good time to consider engine mounts. I definitley didn't like poly tranny mounts years ago, unsure how I will feel about poly engine mounts. Are there firmer than OEM styles that will reduce the engine shaking... that won't also be a trade off for other subjective complaints? And I've read they are a major PITFA to R&R.

 

I would probably start with poly engine mounts, the OEM rubber ones don't hold up very well.

 

I've now acquired a decent exhaust leak. Normal exhaust shop booked through next week so I had a different shop look at it. Clean break in the passenger side ARH collector weld, right at the end of the reducer all the way around. The y-pipe side is hanging down perhaps 1/4". Their opinion was that in the previous shop's goal of reducing the rattling at that suspension brace, they made the exhaust system too stiff. Part of the issue could have been my wild ride through a dimly lit construction lane the end of November. Either way, today's shop said I should install flex pipe in the system to allow the primaries to rock with the engine torque but reduce how much movement was in the remainder of the system. They can simply re-weld the pipe but won't guarantee it. What's the consensus on using flex pipe in our exhaust systems?

 

Cant comment on the flex pipe..but as previously said I would start with poly motor mounts.

 

While I'm not sure flex pipe is a solution here, I would look at all exhaust mounts to be sure they are intact. Usually not many involved, but what's there needs to be good.
I think if the present break is welded properly, it should hold up well. The Y-pipe should be one solid piece, no flex pipe involved there. A good properly welded and mounted system usually will not have any flex pipe or joints. My Tahoe (I know, different situation) has absolutely no flex joints or flex pipe and being a truck, gets jolted around a bit. The rigidity of the system actually supports itself better than if a flex joint is in it somewhere, in my opinion.

 

A few good wacks with a hammer, not the prettiest but it will certainly work

 

I never join the right and left sides of dual exhaust without a good flex connector, I would use one on one side ahead of the "X" and if you have a lot of pipe another in front of the mufflers.
Good ones are not cheap, stainless bellows with a stainless flex liner are the ones I've had good luck with.. note,, this is on Jeeps and off-road vehicles... Where the twist of
the chassis can really wrench on teh exhaust, but just observationally a car launching hard twists stuff up pretty good as well

I've also seen a puller truck that used stainless tube, with one side of the joint expanded back about 10"
so one piece fit inside the other and no clamps. It allows twist without any significant leaks.
The expanded side should be the side to the rear so the internal end of the pipe isn't catching flow..