v6 exhaust info

[GEM 13B]

hi,
i work at an exhaust shop and im doing research on the best possible exhaust for v6 commodores, to make the most power. typically we run some 3-2-1 extractors into a single 2.5" exhaust then into a 2.5" cat, a resonator then a straight thru muffler at the rear. now this whole system makes a noticable difference to the power but earlier today i was told about a different system that instead of going from the extractors to a single pipe then the cat, it goes from the extractors to twin 2.25" pipes into twin cats then into a single 2.5" exhaust. this set up is supposed to make 25kw at the wheels more than the single system!?!?! im not too sure about this as 25rwkw is a fair bit of power (approx 40hp more at the engine).
so my question to everyone is what type of exhausts are yous running and what sort of power are you making, bearing in mind that this was on a dead standard engine.
your input would be greatly apprieciated as it will go towards developing more powerful and better sounding exhausts.

thanks.

 

[Mark]

the system you speak of is a twin cat system and obviously will be better then a single for flow purposes. 25kw is pushing it just to change to a twin cat system. the only way to make that much more power is if u have a completely stock exhaust and then put on the whole new system. but if u already have extractors and a single system on it converting it to twin cats wont make that much. it will increase it just not as much as that.
on a standard engine a completely twin exhaust is just too big much like a 3inch but if your running some sort of boost or have got some pretty decent work to your engine thats when a complete twin system would have more benefit.
but like i said before on a standard or near standard v6 the twin cat system is the go. hope that helps

 

[GEM 13B]

cheers, thats just what we thought.

 

[jNINE]

I'm putting a modified rebuilt engine in my VR soon and am putting on some Genie extractors, but one thing we notice on the VR is the 'Y' piece is very restrictive in it's shape. So we are getting a customised section from the extractors to cat similar to the VS setup where so it runs around the other side of the trans to the VR. Should be interesting to see the result in a standard engine.

 

[BobT]

You might be interested in the stock VZ SV6 arrangement. Maybe it's the same for all VZs I don't know. It has a short 3-1 cast iron manifold on both sides (extractors here would sure be good). Two pipes leading to 2 resonatiors and then another 2 resonators or whatever they are. The 2 pipes then come close together and are joined by a connecting piece about an inch long. The pipes diverge again into 2 cats and then join just before the muffler. What that does for performance I don't know but it sure is quiet - too damn quiet.

 

[VNBOY]

i have pacemaker extractors with 1.5 inch primaries(stock cat), and a 2.5 inch cat back with a muffler.

other than that my car is a stock VN V6 S1.

my car stock should prolly pull around 93rwkW, and i am getting it dynoed on saturday, ill tell you how it goes.