Ok I got my new headers pic is here:

https://montecarloforum.com/forum/seventh-generation-monte-carlos-40/lady-deuce-got-her-tubes-untied-46598/

I have mafna flow catbacks already and resinator delete. Is there any modification that would enhance the exhaust further?

Someone on F/B said something about a better down pipe, what's wrong with the one Thorley sent me?

I want to do this install right!

Thanks Guys

 

I would assume the Thorley downpipe is fine. They custom built this stuff for this car.

 

Mike you are the performance mod guru here. So this exhaust system will be good as is with the cat backs and headers? Or do you have some ideas on further improvment?

 

Are you still running the factory 2.25" exhaust pipes? If so stepping up to 2.5" would give your car a deeper sound. My exhaust guru told me the only way to really change the sound is to go to larger pipes.

 

Yep my cat backs are actually 2.5" and the tips 3" thanks tho Zippy

 

Tad:
With all V-8's I have always been a fan of running "True" duals. Whether you run an X or H pipe setup. However on these with the motor in there sideways... Its definitely an impossibility. ... I believe your Thorley setup is definitely the "HOT" setup for yours!

I think the only other improvement that may possibly work...
Would be to eliminate the cat completely.. and use some fake/electronic replacement 02 sensors to trick the computer into believeing its running at the correct mix and find a shop that that would be able to make that happen for you out of stainless to keep that clean look underneath.

Would it be worth it? I'm not sure... Unfortunately these cars also are not designed underneath for a true dual setup. With out tunneling the floor boards to make it functional as well as look correct.

But hey,
If moneys no option... anything is possible.

You'll be just fine with your Thorley setup!
Its the correct setup for your Monte IMO.

 

Thanks David! yep dumping the cat may not be woth while I guess and hardly anyone would take it off here in MI as it would be illegal

 

Illegal? in Michigan? whos gonna check?
We haven't had AET testing in eons.... So unless its still under warranty...
Losing the Cat is no biggie...IMO. I don't see AET testing ever returning.. Which is fine by me.
Unless, you plan on moving to a state that does vehicle inspections ... before you can plate them ..Then yes I agree to keep the cat on...But here in Michigan... Its not really needed. Just 1 more thing that will eventually dip into your pocket to do a replacement when the need arises.

Cause lets face it...
Yours is definitely not a "stock" Monte Carlo...
That's why I agree with you for the addition of Headers! Just one more big step in building yours to perfection.

 

Ill ask the installer about a cat delete. What about back pressure?

 

Back pressure is not an issue... Since your running a full exhaust system...

If you chose to run just the headers and no exhaust system.. You would lose /partial or all the bottom end torque. Low compression motors do not run well with out back pressure. They use more fuel trying to get up to speed etc...

That's why the high compression motors of rails and funny cars do so well with zoomies etc.

With yours,
The bends in the pipes and mufflers, tails etc... Its a non issue.
Worst case scenario... It will improve flow/performance...

Like I mentioned before...
You will need the electronic replacement 02's to keep the computer in check to eliminate a CEL.
Or have that code deleted from your computer all together... Jason (Maniac) would know more about that electronic aspect.