are the 4480's the comp pacies?
i got them and they definately improved the power downlow for me!

PH4480 are the comp pacies, they are designed to improve midrange.

1 1/2 inch long primary headers is the go, good for 1800-3000rpm. alot or usable torque down there.
anything bigger will be an overkill unless its got a big cam, ported & chipped of cause.

Remi: are your pacies the same as the jackals?

Have a look at this. It is about basic principles and ive stuck to it and it works.
Smaller primaries are much better then the larger ones unless you can rev to about 7000rpm

the rest of the article can be found here, well worth a read
http://www.carcraft.com/techarticles/868/index.html

"""Much of your cylinder head work is diminished if you are running stock exhaust manifolds and mufflers. Exhaust headers are louder and require more attention than cast iron manifolds, but they offer substantial power advantages. While most aftermarket performance headers are of the standard four-into-one collector design, many street applications could make better use of the old four-into-two-into-one Tri-Y design, which broadens the torque curve and is still capable of making power up to about 6000 rpm. These headers are more expensive and time consuming to produce; hence, they are only available from a few manufacturers.

One of the biggest mistakes made in exhaust-header application is the selection of primary tubes that are too large. Big primary tubes are only necessary to carry the gas volume generated at high engine speeds. Most headers with 1-1/2-inch primary tubes will carry an engine well into the 300hp range, while 1-5/8-inch headers can support up to 400 horsepower, and a little beyond in some cases. This depends a great deal on displacement and engine speed. We have seen 1-3/4 headers support up to 550 horsepower without affecting power on a single four-barrel 350 Chevy running at 7500 rpm. Meanwhile, a 480hp, twin carburetor 302 Ford running at 8000 rpm gained 13 horsepower by switching to 1-7/8-inch primaries. It is usually better to err on the small side for a street engine so that torque remains strong. Pipes that are too large generally hurt the bottom end more than small pipes hurt the top end.

Exhaust-system backpressure--as a result of restrictive mufflers, catalytic converters and multiple sharp bends in the exhaust system--can be severely detrimental to good torque and power. Exhaust-pumping losses caused by restrictive exhaust backpressure can be substantial in some applications, and the problem increases dramatically with engine speed. Performance camshafts are also rendered less effective because backpressure typically negates any improved cylinder scavenging during the overlap period. The Catch 22 with exhaust systems is your own personal comfort with the sound level of the mufflers. You can run mufflers with virtually no restriction, but the drone may drive you crazy the first time you take a 100-mile trip. The best approach for most street engines is to complement all the other torque-building efforts you have applied by using a Tri-Y header with at least 2.5-inch diameter exhaust pipes and the least restrictive muffler you can stand relative to sound levels. A crossover tube to balance the pulses from each cylinder bank can help smooth the sound a bit, and it may add a very slight amount of torque depending on the rest of the application. It is usually worthwhile"""

I use wildcat 21x headers, they're 1 1/2 inch primaries try-y design. they are awesome due to the fact that they are cheap $250.00 going into standard AU cat 2 1/4 inch then into 2 1/2 straight throu supercat convertor sport exhaust $280. and they work very well. in my case, better then the comps I got rid off. throttle response was instantaneous, you can feel the torque pulling you along between 2200-3500rpm. rpm needle moving slowly in second gear but the speedo needle reaching 90kmh fast. tell you one thing, no flat spot or lag there bro. engine doesn't sound like its over revved with speed it was going with the open exhaust.

a balance setup works better.

Nah I actually got a new Hi-flow Magnaflow Cat last year as the old one s**t itself after bing slamdunked too many times on Speedhumps etc. I have only got HM headers and a Redback Sports Exhasut with a K& N Filter. So now how do I go about keeping everything in proportion

refer to Dellboy999 comments on previous page {restrictor plate behind the cat, give that a try first. get the exhaust shop to make it into a funnel shape with the 2 1/4 inch outlet facing back towards the redback. it'll sit inside the 2 1/2 inch haust pipe. think of it as a cone over for you exhuast like pacemaker design.
It cost me money to get it right so that it doesn't interfere with the ECU to much. You can sell the HM headers and get something with the smallest primaries, like wildcat 21x. As I recall HM have bigger primaries, could be wrong.
get a Tickford snorkle as well.

I got a restrcitor plate/funnel put behind my cat which connects to the 2.5in redback sports exhaust. It'about 5inches long starts at 2.5in on the cat and funnels down to 2.25inch. It was an off the shelf product. Guy put it on because my cat was empty and said it would get the back pressure just right and increase exhaust gas velocity. I was a bit sus at first because i wanted 2.5in all the way through, but my car has picked up good power through the entire rev range.

The bloke that did my exhaust new his stuff. not like half the wankers i have talked too that think bigger is always better. Like 3in exhaust on excel's and owners wonder why they have lost power.

Cheers Luke..

cheers luke.

Last edited by EL_Fairmont on Sat Sep 10, 2005 3:23 pm, edited 1 time in total.

there you go might be alot cheaper having a funnel restrictor like EL_fairmont mentioned then fooling around with different setups$$$$.
I love it when we put our heads together. at the same time, save some bucks as well

cheers fellows

SOME MORE INFO I FOUND ON A SEARCH;

Too big an exhaust, and the momentum of the out-flowing air from the cylinder is lost. The whole principle fo extractors is to try to not only eliminate back pressure, but also to try and maintain the velocity of the gas flow, so that it sucks out the next exhaust stroke behind it!!!
Bextor was not far off the mark, although he's wrong when he says that it's back pressure that makes the power. The probelms is, that too big an exhaust actually MAKES back pressure at lower rpm!!!

The reason being, if there is too big an exhaust behind the engine, the exhaust gases lose velocity, and there is none of the suction benefit of them drawing out the gases of the following exhaust strokes - the whole principle of what makes extractors work in the first place. Daniel Bernoulli's principle hard at work. Loss of velocity=gain in pressure. There's now back pressure in your exhaust!

The resulting sound of a too-big exhaust will be that awful BLAAAAAAAAAAAH of a well and truly oversized, poorly matched, poorly thought out setup. Commonly seen on 18 year olds cars. :rofl:

A proper match will give that awesome, throbbing, powerful sound of a system that is doing the job. It's easy to tell once you've heard both.

The benefit made by a good extractor/exhaust system is achieved as it takes out more of the burnt mixture from the cylinders with it - a process called SCAVENGING. The result is a partial vacuum remains in the cylinder (instead of burnt mixture), which draws more fresh mixture in on the next intake stroke.

Just thought I would throw someting into the discussuion!

I think you can have too big an intake as well!! I have just fitted a 2.5 inch mandrel bent stainless steel intake from the aircleaner box to the Throttle Body. (ex TazzieTim)

Admittedly my car is on gas and has the restriction of a 40mm gas mixer, but the amount of difference in torque up to 4000rpm is amazing. And thats on both 98 RON petrol and LPG. It has completely transformed my car. (EL i6 Fairmont)

This thread threw me for a while as yesterday I had booked my car in for a set of Pacemaker 4480s HPC coated & new 2.5" CAT. I had previously installed a Lukey 2.5" mandrel bent sysetm. Well I went through with it and have not noticed any flat spots whatsoever. I am thoroughly impressed.

I understand now its is all about havinga good Balance of Energy Dynamics here. Like if you got a good set of Headers but s**t exhaust system and vice versa you are literally going to lose power which is what ironically I am doing with my set-up. keep up the Good work Folks with this think tank process