Need to hear your positive or not experience with a good auto exhaust shop in BR

Buy a new car, that's what the OT does

What kind of vehicle?

Bubb Rub

Always a favorite.

'07 300C 5.7L HEMI.
I decided to keep it when it came time to buy a new one. I'm well aware of the overwhelming demographic that drives these things. I like it a lot and decided that having done this all my life I wouldn't let a car go that I really liked and I really like this car. I don't care what anyone else thinks. It had 108,000 gentle miles on it when it went down.

A local mechanic changed the oil and put the wrong oil in it and the MDS malfunctioned and caused a piston to fail. Phenomenally the damage was minimal.

An employee who is a mechanic that works with me asked to take a look at it and had the engine out of the car before I knew it. He'd already re-built two diesel engines recently so we went ahead and took it down to the short block and had the bad cylinder re-sleeved and all of them honed. Got all new pistons, rings, lifters, heads, catalytic converters etc and put it back together and it runs great.

The only problem is what appears to be a resonance that sets up when decelerating from around 23 mph. It goes away if you downshift I think because it changes the harmonics of the exhaust due to the change in RPM's.

I've tried some things myself but I nor anyone I know has much experience with exhaust systems other than taking them off and putting them on.

I'm hoping someone with years of experience can tell me what to do other than replace the converters which is costly. I'd glady replace the pipes and mufflers if that would cure it but I don't want to do that unless I'm fairly convinced that will cure the issue.

I want to hear about someone who you know of that you think I can trust. I can give you the name of a good transmission shop and I hope someone can do likewise with a good exhaust shop or mechanic.

Just cut the cats off and go straight pipes

it would be nice if that's all it took.

when we first put it back together we didn't get them on tight enough and they worked loose.

I'm always amazed at actually how loud an un-muffled engine is. Exhaust systems are pretty interesting. There's really a lot going on there. They have to be tuned to the particular engine to work properly.

Thanks for the recommendation. I'm calling them in the morning.

quote:

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Rattling is usually a loose weld or a bad hanger

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This is correct. I assure you there is nothing loose and rattling. It's not a rattle.

It sounds and feels like reverberation caused by a resonance that occurs at a particular rpm when decelerating under 23 mph.

The fact that it instantly goes away when you downshift while it is occurring and the fact that everything is tight from stem to stern on the exhaust system doesn't point to any kind of rattle from something being loose.

It is actually coming from the engine itself. I believe it's the exhaust when it hits a certain frequency and volume at just the right conditions.

I believe it's the exhaust also because I have been able to change it by putting clamps on the exhaust pipe at various locations and it changed the frequency of the resonance.

Since I was able to affect it doing that I believe it is coming from the pipes and not from the engine block or anything in that area.

Have you tried loosening the clamps and looking for signs of rubbing? Sometimes everything feels good and snug but the exhaust is rubbing on the facia or other areas like the heat shield.