Exhaust Mods

[Khipset]

Vehicle:
2005 Chevrolet Impala

Engine:
3400 LA1

Mods:
180 Theromostat
200A High Output Alternator
8mm AC Delco Ignition Wires
Custom FWI CAI: 2.5" piping to K&N Filter
EGR Delete
MMS PCM

Mods to come (all head work):
Light Polishing on Intake Ports, Heavy Polishing on Exhaust ports
3500 Valves


Current Exhaust setup:
Currently, 2.25" Pipe from Stock Exhaust Manifold to Mufflers, Cat Delete, U-Bend Delete, and Resonator Delete. Was single muffler when I bought it. Replaced with Flow Master 44 2.5" In/Out and the one day I got off to have the Y added and second muffler they were out of Flow Masters and they talked me into an IMCO. Sounds pretty good, inside and outside looks exactly like a Flow Master, Also 2.5" In/Out.

Problem:
Too much Low End loss with Resonator Delete. Too much High end loss with Magnaflow Resonator.

Misc:
Stock Sweet spot was 3-4.5K, but still have some more pull off the line. Currently it will start to pick up around 3k, but is best at 4-5.5K

I got the stock resonator replaced because when I did the cat delete I got a little bit of rasp. The Magnaflow removed the rasp and I Loved the sound it gave. At idle, perfect deep tone, and when you pushed on it, it was just loud enough to know you're there.

I no longer have the stock resonator to go back on.

My Objective is to keep the High End, but bring the Low end back. I can deal with what ever the sound if I can get the performance I want, however I would like to use the Magnaflow.

The Magnaflow is 3" In/Out - I was thinking about going to a 3" Down Pipe, and 3" to the mufflers and putting the Magnaflow back in. What do yall think about this?

I am more than open to other ideas $300 and less.

[bszopi]

3" exhaust for your current mods is WAAAAY to big. There are guys pushing close to 300hp that don't use a 3" exhaust. I would do a 2.5" all the way back to the mufflers. The downpipe is a huge restriction on these things, so a 2.5", mandrel bent downpipe will help out tremendously.

[robertisaar]

3" exhaust for your current mods is WAAAAY to big. There are guys pushing close to 300hp that don't use a 3" exhaust. I would do a 2.5" all the way back to the mufflers. The downpipe is a huge restriction on these things, so a 2.5", mandrel bent downpipe will help out tremendously.

X2, thats likely where all the power is disappearing due to the exhaust slowing down too much. hell, my el camino(355/jumbo cam) has 3" exhaust(true duals) and sometimes i think thats too large

[Superdave]

Swap to a set of "header style" manifolds from a '04 3500 Malibu, run 2" pipes off those merged into a 2.5" mandrel bent system. More than enough flow.


2.5" exhaust is good for up to around 300 crank HP, any more than that and 3" single or going to true duals is needed.

[Khipset]

Swap to a set of "header style" manifolds from a '04 3500 Malibu, run 2" pipes off those merged into a 2.5" mandrel bent system. More than enough flow.


2.5" exhaust is good for up to around 300 crank HP, any more than that and 3" single or going to true duals is needed.

I have not seen a 3500 installed a vehicle. On the Malibu are they actually "Header style" or do I cap off the Rear and run the pipe in place of the Cross Over?

[IsaacHayes]

They are like shorty block hugger headers basically. dual exhaust with short runners. They do not connect on the engine, they merge under the car to a Y pipe back into one pipe.

[Superdave]

Yep, on the Malibu they merge under the car but it is possible to have the front one crossover the trans like the stock setup does.

[Khipset]

Did all the 2004 Malibu's have the "header style" exhaust manifolds?

[Superdave]

Did all the 2004 Malibu's have the "header style" exhaust manifolds?

If it had a 3500 then yes.


The only problem is that in the Malibu the cats mount right below the manifolds, so if you have a good yard they can cut the flanges off the cats, if not then i think Forced_firebird was selling flanges that bolt up to the 3500 manifolds (or you could have some made).


It's a fairly simple 3 bolt flange.

[Khipset]

There aren't any decent yards around here that have 99 or newer vehicles that I know of. I was looking online at car-parts.com for them but unfortunately they don't have pictures.