VS 5L Exhaust Advice

[Scrubmonk]

I've spent too much money on an exhaust system, that I am still not happy with. Boomy at about 1500-1800rpm, and overall a bit too loud for my neighbourhood. I am after a bit of advice on how to get rid of the boom, and still have a decent high performance system.
My specs are as follows:
VS commy with 5L V8 - stock bottom end, mild Wade cam, roller rockers, 70mm throttle body, Greenfoam tune.
Pacemaker tri-Y extractors into 2.5" twin system
Twin 3" Magnaflow cats, with ends tapered to suit 2.5" system
H Section balance pipe
Twin 2.5" lukey turbo mufflers
Twin 2.5" hotdogs (short - only about 6-8" long) at the rear
Twin 2.5" s/steel tips

The cam and extractors understandably make the car a bit louder than stock.

It has been suggested that the cats are the problem, and I should go back to 2.5" cats. I have also thought about installing a Tru-X cross pipe instead of the H section balance pipe, and/or replacing the rear hotdogs with longer 2.5" resonators, or maybe merging the rear into a straight 3" pipe.

Before I spend anymore money, I would be interested in getting a few opinions from those in the know.

[VR38]

Cams, cats, extractors play little part in exhaust noise, the type and design of the mufflers is where it is at, thats why they call them mufflers, get some mufflers that suit your taste. JMHO.

FWIW hotdogs do little to quieten things.

[Not_An_Abba_Fan]

Super turbos are a very drony muffler. Twin 2 1/2" will always be loud. I recommended changing to 2 1/2" cats to reduce the drone, not to make it quieter.

Putting an X pipe in will make it quieter, but it will also change the quality of the note, less barky, more rumbly. It will also move the torque curve lower in the revs giving you more punch down low.

I would recommend fitting an X pipe AND changing the mufflers to a straight through glass packed design if you wanted to keep performance and make it quieter and less drony.

The cheapest fix is fitting a twin in twin out rear round rear resonator.

Cams, cats, extractors play little part in exhaust noise, the type and design of the mufflers is where it is at, thats why they call them mufflers, get some mufflers that suit your taste. JMHO.


FWIW hotdogs do little to quieten things.

And FWIW, cams, cats and extractors make a big difference to exhaust note over stock items. The cam not so much but cats especially, then extractors.

[Scrubmonk]

Super turbos are a very drony muffler. Twin 2 1/2" will always be loud. I recommended changing to 2 1/2" cats to reduce the drone, not to make it quieter.

Putting an X pipe in will make it quieter, but it will also change the quality of the note, less barky, more rumbly. It will also move the torque curve lower in the revs giving you more punch down low.

I would recommend fitting an X pipe AND changing the mufflers to a straight through glass packed design if you wanted to keep performance and make it quieter and less drony.

The cheapest fix is fitting a twin in twin out rear round rear resonator.



And FWIW, cams, cats and extractors make a big difference to exhaust note over stock items. The cam not so much but cats especially, then extractors.

Thanks for your advice. When I first had the exhaust done, they put Lukey sports mufflers (just an S bend inside), and they were just so so loud I took it back and had it swapped over the turbos which quietened it down. What would be your choice of muffler? It is probably just cheaper to merge it after the cats into a single 3" system.

[Not_An_Abba_Fan]

The cheapest fix is to fit a rear resonator.

I would use similar mufflers to what you had originally, but with the X pipe to make it quieter.

[GTP 85]

scrubmonk. I installed a supercat (round) twin 2.5 inlet/ outlet rear ressy on my twin 2.5 exhaust. That definitely took the edge of the sound. Made it much deeper and plesant sound in the cabin, and knocked the outside note down a bit.

I bought it in as new condition off a bloke who bought full supercat system for his ls1, but didnt want the ressy. bargain at $50 with tips

[Scrubmonk]

Bit of an update...
Just replaced the Lukey Super Turbos with some flow through Magnaflows. Also replaced H balance pipe with Magnaflow Tru-X cross pipe.
Quite a bit louder and deeper note out the back, and sounds very sweet at WOT.
The booming inside the car is much the same, maybe in a narrower rev range than before. Definitely not boomy at idle like it was with the Super Turbos, just a nice deep rumble. I will drive it like this for a while, but I will probably end up adding a rear resi just to keep my sanity.