New From San Antonio
Welcome to the forum!
You got a great deal on your 2003 SS. The 3800 Series II engine is one of the most reliable engines GM has made in the last couple decades. And one of the most popular. Which is a good thing for you. It means there's plenty of stuff available all over the internet for them.
When searching the net for engine stuff, it may help your search by looking under Pontiac Grand Prix as well as Monte Carlo. Since the Grand Prix used the same engine. You should have the non-supercharged L36 engine in your Monte, unless someone swapped it out.
One common first mod on the 6th generation Montes, is something called a "U-bend delete".
There is a U-shaped kink in the exhaust; just before the catalytic converter. GM put it there to make room for a sensor, and to add some back pressure. Many people here have cut that little section out and replaced it with a straight piece of pipe. You can buy the U-bend delete premade online. Or you can go the cheaper and easier route.
Stop in at a local independant muffler shop and get to know them. All you really need them to do is this:
Cut a short piece of straight pipe the proper size. Drill a hole for the sensor, and weld on a captive nut to screw the sensor into. Cut out the stock U-bend section of pipe, and install your replacement piece. With the sensor sticking out sideways instead of upward. Secure into place and you're done.
But most people who do this also change to a high-flow catalytic converter, and an aftermarket performance downpipe while they're at it. Those are the pieces on either end of the U-bend.
And if you're doing that much, you may as well go with the "cat-back" exhaust system of your choice. There's many to choose from. And it depends on what your preference is for sound levels. Some people like their exhaust louder than others.
Have we spent enough of your money yet?
LOL j/k
You got a great deal on your 2003 SS. The 3800 Series II engine is one of the most reliable engines GM has made in the last couple decades. And one of the most popular. Which is a good thing for you. It means there's plenty of stuff available all over the internet for them.
When searching the net for engine stuff, it may help your search by looking under Pontiac Grand Prix as well as Monte Carlo. Since the Grand Prix used the same engine. You should have the non-supercharged L36 engine in your Monte, unless someone swapped it out.
One common first mod on the 6th generation Montes, is something called a "U-bend delete".
There is a U-shaped kink in the exhaust; just before the catalytic converter. GM put it there to make room for a sensor, and to add some back pressure. Many people here have cut that little section out and replaced it with a straight piece of pipe. You can buy the U-bend delete premade online. Or you can go the cheaper and easier route.
Stop in at a local independant muffler shop and get to know them. All you really need them to do is this:
Cut a short piece of straight pipe the proper size. Drill a hole for the sensor, and weld on a captive nut to screw the sensor into. Cut out the stock U-bend section of pipe, and install your replacement piece. With the sensor sticking out sideways instead of upward. Secure into place and you're done.

But most people who do this also change to a high-flow catalytic converter, and an aftermarket performance downpipe while they're at it. Those are the pieces on either end of the U-bend.
And if you're doing that much, you may as well go with the "cat-back" exhaust system of your choice. There's many to choose from. And it depends on what your preference is for sound levels. Some people like their exhaust louder than others.
Have we spent enough of your money yet?
LOL j/k
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prickly_pete
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Dec 5, 2011 03:39 PM
















