Exhaust Systems

[Daniel Gray]

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]

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]

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]

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]

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]

*louder!!!

[pandaman]

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]

Oh and single 2.25 is what these things run stock I think.

[pandaman]

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]

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.

[ashzv6]

hi guys n galz
i got a redback system off ebay for my v6 vn non irs

silent on idle and wen you take you foot of but
when you put it down it boots and lets out some nice noise
i definetly noticed a power increase but my old exhaust was leaking, had mass holes in the 1st muffler and had rust holes and cracks all the way up the stock pipe. it was the factory pipe so no surprises.

i recomend the redback exhausts but you might be able to get something cheaper.
for quality and performence compared to stock i give it 5/5

[adam69]

i have a VQ V8 with a redback 2.5inch and its much better than stock.i thought it was a bit quiet so i had the rear muffler removed and replaced with a straight through pipe(redback supplied from memory)and it was heaps louder.depends on your tastes though.I kept the rear muffler incase anybody complains about the noise.

[Daniel Gray]

i have a VQ V8 with a redback 2.5inch and its much better than stock.i thought it was a bit quiet so i had the rear muffler removed and replaced with a straight through pipe(redback supplied from memory)and it was heaps louder.depends on your tastes though.I kept the rear muffler incase anybody complains about the noise.

did u get the muffler with twin exits or single?

[adam69]

I got the single one but i have a twin 3in chrome tip that drops out the back.looks great.

[coolvxss]

I have a 2.5 inch redback catback. I had the 2 mufflers and it sounded alright but it was a little quiet for my liking so i took the rear resinator off and now its sweet as. I still kept the ressie just incase i have to put it back on at a later stage.