LS Exhaust Comparison Gold! HSV Headers vs Aftermarket Tri-Y's & 4-1's. What would you choose?

[Rikster71]

id recommend c & a autofashion, the 2.5 catback system 1 3/4 headers would be great and with the cai youll be saving some petrol with a better tune. if your not wanting it too loud at certian times youll have the bimodal function to quite it down aswell!

Thanks Dimetime, but why? I get it’s your recommendation, but can you help me understand the differences between the 2 setups. I see a lot of people recommending going with HSV 340 system, I’m not sure what the differences are other than mid length Tri Ys.

 

[dimetime]

Thanks Dimetime, but why? I get it’s your recommendation, but can you help me understand the differences between the 2 setups. I see a lot of people recommending going with HSV 340 system, I’m not sure what the differences are other than mid length Tri Ys.

The hsv header design is not bad, up until the cat, the collecter into the cat is very narrow, that combined with the 400cell cats the top end will suffer.

Anyone whos serious about getting the most out of there hsv tri ys will have the cats and inlet changed into 3 inch and 200 cell cats.
https://forums.justcommodores.com.a...ance-vf2headers-and-cats.264534/#post-2896377
read more about it here.
My main recommendation come from the fact that the exhaust noise isnt going to change much from standard to hsv, sure it will be alittle louder but at the end of the day, your changing the exhaust for sound aswell as performance, and the difilippo system does both the best in my opinion!

one of the forum members did a comparison between his dpe system and standard, listen to it with headphones and you can easily tell why most guys end up the difilippo system

 

[TTubrag]

Thanks Dimetime, but why? I get it’s your recommendation, but can you help me understand the differences between the 2 setups. I see a lot of people recommending going with HSV 340 system, I’m not sure what the differences are other than mid length Tri Ys.

Aaaand.... availability.
HSV kit is getting hard to find. Especially in good condition. And even more so especially, full systems.
= getting more expensive.

Given the time and money you’d spend looking for good HSV kit and knowing some of the downsides of it, you arguably should consider just going aftermarket with quality extractors and mid-section into your stock bi-modal mufflers.
Difilippo and Manta give a deep note with quiet 2.5” mid-section options (although they’ll be a little louder than stock).

 

[Rikster71]

Thanks guys, some good food for thought.

 

[[paradox]]

Aaaand.... availability.
HSV kit is getting hard to find. Especially in good condition. And even more so especially, full systems.
= getting more expensive.

100% this, at the start you could pick them up cheap as chips as they were mostly being scrapped when swapping to aftermarket
now people somehow think used hsv complete systems are made from gold, many are now 100k + kms old, and these are mild steel systems

 

[426Cuda]

They're stainless actually.
Dimtime is right. The cats are the restriction. But, the 340 ones are much better than the 325's, especially at the cat entry point.
In my opinion it's worth the search if you want to keep the OEM look. It's not OEM, but it's as close car you'll get. But, given how hard they are to find and the fact you're tuning (so, assuming you're not concerned about warranty), I agree with the others. Go aftermarket.

 

[Rikster71]

Ok so pulling this all together, here are two options;

1. I actually have access to a set of HSV 340 Headers, interestingly it doesnt have cats attached, I can also just buy a HSZ centre pipe that was taken off under 10k, no damage for $200, or HSV Cat Back but the mufflers with Vacuum Bi Modal for $450, which of these would you go with and what 200 cell cats would you recommend?

2. Genie Tri Y's with 200 Cell Cats into either of the above systems, I want to retain my Bi-Modal i also waned to retain as original look and feel, so not interested in polished stainless steel etc, so what catback, or centre pipe options are worth considering for a 2.5 system.

 

[426Cuda]

Ok so pulling this all together, here are two options;

1. I actually have access to a set of HSV 340 Headers, interestingly it doesnt have cats attached, I can also just buy a HSZ centre pipe that was taken off under 10k, no damage for $200, or HSV Cat Back but the mufflers with Vacuum Bi Modal for $450, which of these would you go with and what 200 cell cats would you recommend?

2. Genie Tri Y's with 200 Cell Cats into either of the above systems, I want to retain my Bi-Modal i also waned to retain as original look and feel, so not interested in polished stainless steel etc, so what catback, or centre pipe options are worth considering for a 2.5 system.

I'd get some good bullet style 3" cats and have the exhaust shop weld up inlet, outlet and flanges. Whack these on with your HSV mid-section and the stock rear mufflers and it will go better and sound great.

 

[Rikster71]

I'd get some good bullet style 3" cats and have the exhaust shop weld up inlet, outlet and flanges. Whack these on with your HSV mid-section and the stock rear mufflers and it will go better and sound great.

Thanks Cuda, any recommendations on the cats, research had pointed me towards HM’s but obviously they are no longer available.

 

[MY17DIR]

I personally will be looking at magnaflow 200 cell cats to go with my 340 headers and mid section, unless someone advises otherwise.