will high flow cats outflow hsv headers?

[johnno010684]

hi guys, i read a post somewhere with someone stating there is no point adding high flow cats when using tri y's or hsv headers because stock cats will outflow them? anyway i want to keep my hsv headers as i dont see the point in spending 1k for pacies for only a few more kw's, if stock hsv cats outflow hsv headers is there any point adding high flows? hopefully someone with more exhaust knowledge can help me out.

[Munz]

I add hiflo cats to all my cars

they cause a enough restriction for me, so I change them


http://www.surefloexhaust.com.au/balistic_cat.htm

[wraith]

It's not just about the couple of kw's. It's about increasing your engines efficiency as well. I think from memory the HSV cat's are no different to standard in regards to build and material used.

[DLFHUB666]

They will flow enough for a stockish engine (OTRCAI/Mafless tune/catback) but who wants enough, when you can have more.

[Crisis63]

What did look restrictive was the pipe that led in and more so the one that led out to the exhaust system on my car. They were squashed on the bends . I had a 2.5” cat back system on my car when I bought it. I put on Pacemaker Tri Ys. All that was left were the standard cats. My bro said he had tested them and can’t measure a difference between standard cats and hi flow cats. I was offered a too good to miss deal on some hi flows with 2.5” pipe that has better bends so I took them. Haven’t had the chance to rope them in as yet though.

[johnno010684]

They will flow enough for a stockish engine (OTRCAI/Mafless tune/catback) but who wants enough, when you can have more.

its far from a stock gen3

[johnno010684]

just trying to source out some exhaust variations before i get a mafless tune

[Vt_vic]

if its far from a stock gen 3 then high flow cats would be the first thing i would get

[johnno010684]

thats the main question i was asking, if the hsv headers only flow so much then high flow cats arent gona change the exhaust flow.

[TI3VOM]

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[Not_An_Abba_Fan]

When you are talking dyno readouts, any exhaust is a restriction. The stock cats will flow enough for the street, but if you are wanting top end performance, then high flows are the way to go. Be careful though, if you want to stay legal, 200 CPSI cats are the highest flowing EPA legal cats.

I can do Hurricane 1 3/4" or 1 7/8" primary 4-1's and high flow 200 CPSI bolt on cats for $1295 shipped. Or you can go universal cats, but then the pipework will have to be fabricated in 2 1/2", combined it would be $1130. For the extra $165, I would go the bolt ons, then you can fit it all yourself. Comes with all gaskets too.

[johnno010684]

When you are talking dyno readouts, any exhaust is a restriction. The stock cats will flow enough for the street, but if you are wanting top end performance, then high flows are the way to go. Be careful though, if you want to stay legal, 200 CPSI cats are the highest flowing EPA legal cats.

I can do Hurricane 1 3/4" or 1 7/8" primary 4-1's and high flow 200 CPSI bolt on cats for $1295 shipped. Or you can go universal cats, but then the pipework will have to be fabricated in 2 1/2", combined it would be $1130. For the extra $165, I would go the bolt ons, then you can fit it all yourself. Comes with all gaskets too.

hmmm... sounds pretty good, what cats are these by the way? i am nearly in the process of buying two high flows from x-plode. i have a twin 3" cat back mild steel x force and i think it sounds terrible but i dont want to buy a whole new exhaust, i was thinking of getting the merge pipe cut out and removing the rear muffler and adding hot dogs. i dont want it to be too loud as it has a nice lumpy cam in it now and dont wana attract too much attention when its cruising, but i still want it nice and deep when the foot gets put down.

[johnno010684]

ok so im bidding on some pacies at the moment, they are 4-1 with 3" collector. see how it goes but im wondering if im better off goin tri y's because id rather low mid range than high end torque as i wont be flogging the car everywhere i go, am i right?

[Vt_vic]

if you dont really go over 2500 rpm and isnt getting cammed then go try y's i personally think there shit in my opinion when i had try y's

[Darren]

Extractors / cats add a handful of kw's (well did in mine ~10kw), there was no further modifications to the tune, the big difference is the torque.

Have a look at the MACE section on the LSX tuning for a bit of a journey I have been through recently.

[one_and_only2004]

Comparing my ute with tri-y's to the exact same setup on a mate's with 4 into 1's there's 5rwkw in it in the peak power (for 4into1), but there's a lot more going into the mid to high torque delivery.
I have shit all more torque than him down low too, and that's meant to be the benefit of tri-y's.

[Not_An_Abba_Fan]

There was a shop in Melbourne that did back to back dyno runs on about 5 or 6 different sets of extractors on the same car, tri Y's, 4 -1's, different sized primaries and collectors. There was only about 5 kW difference between them all, but the torque curves changed as the revs increased. Tri Y's run out of puff before the 4-1's do, thats why people say they are better for bottom end, but what should be said is that 4-1's are better for top end as one_and_only2004 found out, they are pretty close down low.

But, and here is a big but, the more mods you do to the engine the bigger the difference in torque in the higher RPM with 4-1's.

On a stock engine with factory manifolds, 4-1's and high flow cats can add as much as 25-30 kW.

[johnno010684]

clean out your inbox naaf it says its full, i am just waiting on the $ in the next week and will order the system you mentioned for me

[Not_An_Abba_Fan]

Inbox should be clean.