86SS86LS

iTrader: (1)

I have a stock lm7 and would like to utilize the 2" dual exhaust that is already on my monte carlo. Will 2" dual exhaust support a stock 5.3?

Also, my plan is to use pacesetter f-body headers that have a 3" collector. Are there any concerns with stepping down from a 3" collector to 2" exhaust pipe?

Bo185

It will run although not ideal. Its not going to hurt anything but it may get hotter under the car though if you beat on it due to the smaller exhaust.

Daniel0026

I would run at least a 2.5. A 3" would be ideal. What mods have you done/ do you plan on doing to the 5.3? That also makes a difference as well as your plans for the main use of the car...If ground clearance allows, id go for a larger size. Also consider the power output of your old engine vs the new 5.3. The effeciency is much greater with the 5.3 and your overall performance and drivability will improve if you let it "breath" (if clearance allows).

pferris

iTrader: (2)

dual 2" would be a bit too small for the car, a dual 2.5 or 3" would be best. 2 2" pipes flows less then the stock 3" single pipe.

gofastwclass

iTrader: (2)

Honestly it will work fine unless you are trying to run it hard and get maximum performance and efficiency. Even at that point it will only be less that optimum - but will run fine.

I had a SINGLE 2.25" exhaust on my 5.3 swapped Thunderbird for the last three years and just recently (last week) changed to dual 2.5" mandrel bent pipes. I have run that car like I stole it most days and it hasn't missed a beat. Now it revs quicker and feels peppier to the butt dyno but it has never been on a chassis dyno or down a track so I can't A/B a print out of the true difference.

Here are some suggestions blatantly stolen from Magnaflow's web site:



One thing to keep in mind is maintaining air velocity while reducing back pressure. Don't blindly take my word for it, follow the links I provided or read some of David Vizard's writings on the subject.

86SS86LS

iTrader: (1)

Thanks for the replies. I don't want to compromise the potential of the motor with a restrictive exhaust, so I'll plan to go with 2.5 or 3".