Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

Exhaust Systems

Daniel Gray

now a ultra-low cruiser!
Joined
Aug 27, 2005
Messages
31
Reaction score
0
Points
0
Age
31
Location
Newry, Vic
Members Ride
VP V8 Calais, VZ GEN4 SS
Just wondering about what the best exhaust is for a 5 litre. Seems to me, the cheapest way to do it would b 2 pull the rear resonator and slap on some pipe (little bit of bending for IRS). Considering the factory one has 1 cat, going into 2 mufflers in parallel and back into 1 muffler at the back. Of course 2 cats would b better but thats pricey. but performance exhausts for these mostly only have one muffler in the middle, surely the factory parallel mufflers would flow better, help please?
 

pandaman

Aussie Muscle Fan
Joined
Feb 13, 2006
Messages
783
Reaction score
24
Points
0
Age
35
Members Ride
VN Berlina 5.0 A4
This is a topic of constant debate with basically no end. There's a heap of information over on street commodores. Removing the rear resonator and replacing the standard muffler with a high flow one would give some small gains, but probably wouldn't be brilliant. My opinion is that the most cost effective option for a stock/very mild 5 litre is a 2.5 inch catback with one high flow muffler and maybe a resonator depending on what kind of note you're after. For more money, twin cats into twin 2.25 inch with balance pipe and one muffler per pipe. Although I reckon the single 2.5 inch would be the go and use the money you save to go towards decent extractors.

There are other options which may result in the loss of some low end torque on a stock engine but leave some "growing rooom" for further modifications (cam, custom tune etc.). There is the possibility of a three inch catback which apparently gives AWESOME noise and pretty good topend but is a bit sluggish at the bottom end. Another fairly popular system is twin cats into twin 2.5 inch and then back into single 3 inch over the diff with varying arrangements of mufflers. Once again anecdotal evidence seems to suggest a loss of bottom end torque.

I'm actually looking at getting an exhaust for mine, i'm probably gonna just go for a single 2.5 inch, cheap and boring (saving for extractors). :)
 

Daniel Gray

now a ultra-low cruiser!
Joined
Aug 27, 2005
Messages
31
Reaction score
0
Points
0
Age
31
Location
Newry, Vic
Members Ride
VP V8 Calais, VZ GEN4 SS
sweet, thanks for that. the 2.5 inch systems are cheap as aren't they? wot do u reckon are the best? I was at the bairnsdale drags and sum guys wer runnin 2 1/4 cos they reckoned it gave them good low end, one guy even have a twin 2 1/4 on a 355!
 

1991_Vn2nV

New Member
Joined
Mar 9, 2006
Messages
8,718
Reaction score
66
Points
0
Age
32
Location
Gumeracha, Adelaide Hills
Members Ride
91 VN Berlina & 03 VY Berlina
Daniel Gray said:
sweet, thanks for that. the 2.5 inch systems are cheap as aren't they? wot do u reckon are the best? I was at the bairnsdale drags and sum guys wer runnin 2 1/4 cos they reckoned it gave them good low end, one guy even have a twin 2 1/4 on a 355!
A twin 2.25 inch exhaust flows alot more than a single 3 inch.. But a single 2.25 inch is too small for a 5L... And a 355 stroker could do with a bit more than a twin 2.25 inch as well...
 

Daniel Gray

now a ultra-low cruiser!
Joined
Aug 27, 2005
Messages
31
Reaction score
0
Points
0
Age
31
Location
Newry, Vic
Members Ride
VP V8 Calais, VZ GEN4 SS
1991_Vn2nV said:
A twin 2.25 inch exhaust flows alot more than a single 3 inch.. But a single 2.25 inch is too small for a 5L... And a 355 stroker could do with a bit more than a twin 2.25 inch as well...
yeh thats wot i thought, they thought otherwise, but evry1 to their own. Mite give one of those REDBACK systems on ebay a go, but they dont make the IRS ones without a rear resonator, damn. Do u rekon one of those systems would b much loader than standard?
 

Daniel Gray

now a ultra-low cruiser!
Joined
Aug 27, 2005
Messages
31
Reaction score
0
Points
0
Age
31
Location
Newry, Vic
Members Ride
VP V8 Calais, VZ GEN4 SS
*louder!!!
 

pandaman

Aussie Muscle Fan
Joined
Feb 13, 2006
Messages
783
Reaction score
24
Points
0
Age
35
Members Ride
VN Berlina 5.0 A4
I have heard people saying that the redback systems aren't very loud. But loud doesn't neccesarily equal power. Noise is nice though :)
 

pandaman

Aussie Muscle Fan
Joined
Feb 13, 2006
Messages
783
Reaction score
24
Points
0
Age
35
Members Ride
VN Berlina 5.0 A4
Oh and single 2.25 is what these things run stock I think.
 

pandaman

Aussie Muscle Fan
Joined
Feb 13, 2006
Messages
783
Reaction score
24
Points
0
Age
35
Members Ride
VN Berlina 5.0 A4
1991_Vn2nV said:
A twin 2.25 inch exhaust flows alot more than a single 3 inch.. But a single 2.25 inch is too small for a 5L... And a 355 stroker could do with a bit more than a twin 2.25 inch as well...
Depends what the full details of the engine are, bigger is not always better with exhausts.
 

1991_Vn2nV

New Member
Joined
Mar 9, 2006
Messages
8,718
Reaction score
66
Points
0
Age
32
Location
Gumeracha, Adelaide Hills
Members Ride
91 VN Berlina & 03 VY Berlina
pandaman said:
Depends what the full details of the engine are, bigger is not always better with exhausts.
Yeah I know that...But a single 2.25 inch exhaust is not ideal for a 5.0L, not for performance. And a dual 2.25 inch system isnt leaving much room to move for a 355 stroker...I never said it was bad, I just said it could probly do with a bit larger, especially when people with 355 strokers have other mods as well, or atleast plans for more mods.
 
Last edited:
Top