Custom fabricated exhaust

[theprototype]

Anyone get a custom exhaust? I’ve got some quotes from decent shops for under $2k for a full catback system with aftermarket mufflers. I think keeping the stock tips with the distal valves shouldn’t be a problem. Anyone know if this would throw a CEL? If not I think I’m going to go ahead and get this done within the next few weeks

Also if anyone has any shop recommendations in Houston, lmk!

 

[Grainofsand]

How restrictive is the factory exhaust?

 

[WONT TAP]

How restrictive is the factory exhaust?

Not at all. We've already been over 700 whp in both CT4-V and CT5-V Blackwings, with factory cat-back exhaust systems.

 

[CBH]

Here's my write-up:

CT5-V - Custom Exhaust Finally Done !!

I've had several remarks in various threads, so thought I'd create a new one to bring them together. I found the absolute last shop in town that would touch my car, and today they finally did the work. They replaced stock muffler with a MagnaFlow that has a built-in cut-out on each side of the...

www.cadillacvnet.com

I was shocked that every other shop in town turned me down. The work wasn't that tricky at all. Especially with mufflers that have the bypass built in.

I wish it was louder. And the CEL is still on for unknown reasons.

 

[theprototype]

I remember that thread, looks like I even posted in it haha. So I'm thinking now of just replacing the mufflers with something aftermarket because the stock pipes are over-engineered as is and all I'm interested in is making it sound a little deeper. Where exactly are the valves located? I read in another thread that they're somewhere inside the muffler canister but you said in your thread that they're by the tips?

 

[A Blackwing]

Headers with stock exhaust let you keep the valves and no CEL. Much nicer tone. Less heat under hood, more power if you tune for them.

 

[MDM]

The Valves are located between the muffler and the tips. If you look under the vehicle, you will see the actuators. If you look in through the tips, you will see the actual butterfly valve. I totally agree that it needs different mufflers. As a side note, I was very surprised how much louder the exhaust note is when lowering the rear seat backs.

 

[theprototype]

Car is in the shop getting the mufflers replaced. Decided to keep the rest of the exhaust stock since it’s already so over-engineered. This should just help with the sound and keep the performance the same. Can’t wait to hear it in a few hours!

 

[raneil86]

Car is in the shop getting the mufflers replaced. Decided to keep the rest of the exhaust stock since it’s already so over-engineered. This should just help with the sound and keep the performance the same. Can’t wait to hear it in a few hours!

Did you happen to make a "before" recording so you can compare it with an "after" recording? Would love to hear the difference.

 

[theprototype]

Did you happen to make a "before" recording so you can compare it with an "after" recording? Would love to hear the difference.

Nope but you can fire up yours in your driveway and peep the before lol. I’ll share some clips when it’s done. It’s a little different design than CBH’s up there so I’m interested in seeing how it turns out

 

[raneil86]

Nope but you can fire up yours in your driveway and peep the before lol. I’ll share some clips when it’s done. It’s a little different design than CBH’s up there so I’m interested in seeing how it turns out

Perfect. Please do!

 

[theprototype]

Boys. This. Is. It. Oh my god the exhaust note with valves open is pure bliss. Deeper, more punchy, pops and crackles are more like pops and burbles. Switch the valves closed and it’s damn near stock. It’s too quiet lol. Ill post a vid later when my wife can film me giving it some gas but for now here’s a pic of the setup. Valves open and you’ve got essentially a straight pipe. Valves closed and exhaust is shifted to the two magnaflows. No CEL, stock tips.

 

[raneil86]

Can't wait to hear it!

 

[theprototype]

Here’s some short clips with valves open

 

[CBH]

Congratulations !!

I like yours better than mine. Your true straight pipes seem more effective than the "bypass" built into my mufflers.

I'm surprised those tiny Magnaflows do much, but very happy it works. The shop admitted that when they cut my factory tips (with valves open) they accidentally cut off a tiny piece of the valve itself. Perhaps that's the source of the CEL ? It does not make sense to me why there is even a fault attached to the superfluous valves, but it also does not make sense why it's firing when the valves are working fine.

I hate the idea of the $$$ for the headers and tune, but I keep thinking about it.........

 

[theprototype]

I think they're as effective as they are because they used 2.5" 409 stainless which is 0.25" smaller than the stock pipes. So instead of larger pipes going into a more congested muffler I have slightly smaller pipes going into a more free flowing muffler. End result is slightly louder than stock but still muffled with valves closed. And it's not a true straight pipe with valves open because there is still slightly more resistance to flow with the smaller diameter. Don't know the exact physics behind it but the shop has been in business for 50 years now and he said he's used this same setup on a few ZL1's with good results so I said take my money lol.

As far as your CEL this may be oversimplifying it but can you not just order a new valve entirely and replace the damaged one?

 

[CBH]

Probably, but not sure they would get rid of the light. The part appears to function properly, so it does not make sense that the light is even on.

 

[Robbys3m3]

Very nice and love there is no cel! Do you know the magnaflow part numbers by chance?

 

[theprototype]

No idea, they are quite narrow but when the valves are closed sound very close to stock. Possibly because they’re two of them instead of just the one big muffler before *shrug*

 

[Robbys3m3]

Thanks again for doing this..would it be possible to ask the shop if they know the part numbers, or even the muffler length? With either of that my mechanic says he can order the bends and the mufflers and give this a shot for me. Thx in advance.
Rm