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EF ...is my 2.5" exhaust system too big? Opinions please! 

 

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 Post subject: EF ...is my 2.5" exhaust system too big? Opinions pleas
Posted: Mon Feb 27, 2006 1:38 am 
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Hey all,

My current exhaust system is Pacies, Hi-flo CAT, smallish straight-thru muffler, mandrel bend over rear axle, hot-dog resonator then 3" SS tip (all 2.5" to tip).

My engine is stock 4L I6, but I have experienced the following:

1. Before any exhaust mods (std system) - nice smooth response, nippy.
2. Put std 2.5" sports system on from CAT back with lipped tip - nice smooth response, nicer note.
3. Put Pacies on with Hi-flo CAT (kept previous sports system) - note changed, a bit droney & loud, response seemed more sluggish
4. Thought muffler restriction was causing sluggishness, so had muffler replaced on previous system with smaller straight-thru muffler, and 3" unlipped tip welded on = my current system!

The problem is, I still find my current system too loud & droney, and the overall response sluggish compared to when I was at stage 2 above!

I've seen some threads on this site saying that a larger diameter exhaust system can rob power & response, due to the slowing of exhaust gas speed ...could I be experiencing this?

I mean, I had the best note, feel, and response at stage 2 above ...before I added the pacies & hi-flo CAT!

Should I consider going back to a std but smaller 2" sports system from CAT back ...to see if I regain any power, and a quieter, SMOOTHER note?

HOWEVER, I am seriously considering getting the RPD / Alted Stage 2 cam installed next month ...so should I wait to see how my current system will run with the new cam?

...ANY OPINIONS WOULD BE MOST WELCOME!

 

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Posted: Mon Feb 27, 2006 2:09 am 
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i wouldnt bother downgrading your exhaust. not worth the money or effort. if it is to droney ask an exhaust shop to remove the hot dog and put a small muffler in there..

as i siad mine is quiet inside, 400km trip and didnt even notice it, but when the foot is down you can hear it a little inside the cabin and you can hear it going up the street but not from a block away

 

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Posted: Mon Feb 27, 2006 11:12 am 
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You could probably try some pressed bent extractors from the wreckers, although if ya gettin a cam then keep the pacies on.


Cheers............

Last edited by falcon4litreOHC on Mon Jun 26, 2006 1:00 pm, edited 2 times in total.

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Posted: Mon Feb 27, 2006 11:34 am 
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I reckon it might be the cat. The new one might be advertised as a "high-flow" but might flow worse than stock.

 

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Posted: Mon Feb 27, 2006 1:23 pm 
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voxace wrote:
I reckon it might be the cat. The new one might be advertised as a "high-flow" but might flow worse than stock.

Yeah this has been discussed before some "hiFlow " cats DONT :roll: :roll:

 

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Posted: Mon Feb 27, 2006 2:09 pm 
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GTBob wrote:
voxace wrote:
I reckon it might be the cat. The new one might be advertised as a "high-flow" but might flow worse than stock.

Yeah this has been discussed before some "hiFlow " cats DONT :roll: :roll:


Got it done at Mettam's Mufflers, Morley WA.

Any way I can get them to check the CAT flow?

What replacement CAT would you recommend ...or should I go back to stock?

 

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Posted: Mon Feb 27, 2006 4:45 pm 
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I would bet some money if all you did was replace the pacies with crappy lukey pressed bent headers, you would gain all your bottom end power back.
.

Cheers

Last edited by falcon4litreOHC on Mon Jun 26, 2006 12:59 pm, edited 2 times in total.

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Posted: Mon Feb 27, 2006 4:58 pm 
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Yeah the pipes are a tad big on the 4499's, you shouldn't have lost any down low though. Probably just seems that way in comparison to the top end.

 

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Posted: Tue Feb 28, 2006 7:36 pm 
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[quote="falcon4litreOHC"]I would bet some money if all you did was replace the pacies with crappy lukey pressed bent headers, you would gain all your bottom end power back.

I am looking for some cheap $100 extractors at the moment. I have pacemaker 4499's with a magnaflow high flow cat($$$$) and 2.5in cat back sports systems. I too lost a bit of ooofffff down low.

Going to try the 2.25in over the back tailshaft first, been quoted $80 for that.

Spoke to a performance workshop about this today...

For a start, they reckon I shouldn't have gone above a 2 1/4" system.

They also reckon that if I took my centre muffler out (run straight pipe only), and then replaced the hot-dog with a Magnaflo ...I would get all my bottom end back!

i.e. Pacies - hiflo CAT - Magnaflo just before tip = some backpressure, and more bottom end power.

I'm getting these guys to install my RPD Stage 2 cam in about a months time, so will get them to sort out my exhaust then.

Thanks for the advice!

 

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Posted: Tue Feb 28, 2006 8:14 pm 
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falcon4litreOHC wrote:
I would bet some money if all you did was replace the pacies with crappy lukey pressed bent headers, you would gain all your bottom end power back.

I am looking for some cheap $100 extractors at the moment. I have pacemaker 4499's with a magnaflow high flow cat($$$$) and 2.5in cat back sports systems. I too lost a bit of ooofffff down low.

Going to try the 2.25in over the back tailshaft first, been quoted $80 for that.

Cheers




how much do you want for the 4499s?
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 Post subject: Re: EF ...is my 2.5" exhaust system too big? Opinions p
Posted: Tue Feb 28, 2006 8:22 pm 
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markr154 wrote:
3. Put Pacies on with Hi-flo CAT (kept previous sports system) - note changed, a bit droney & loud, response seemed more sluggish


what pacies did you have put on? 4499 or 4480??

the 4499 would result in a bit of dowyness right down low, as they are more of a mid range and over item.

the 4480 will give you back you down low
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 Post subject: Re: EF ...is my 2.5" exhaust system too big? Opinions p
Posted: Tue Feb 28, 2006 8:29 pm 
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tickford_6 wrote:
markr154 wrote:
3. Put Pacies on with Hi-flo CAT (kept previous sports system) - note changed, a bit droney & loud, response seemed more sluggish


what pacies did you have put on? 4499 or 4480??

the 4499 would result in a bit of dowyness right down low, as they are more of a mid range and over item.

the 4480 will give you back you down low


Don't have a friggin' clue!

The muffler guy just looked up the Pacemaker catalogue, and found the ones for my EF ...didn't offer any alternatives.

I have a real drone at low to medium revs, sounds & feels better at high revs.

Will get the performance guys to investigate it...

 

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QUARTER MILE PB: currently 14.590 @ 96.00 mph ...BOOST AHEAD!!

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Posted: Tue Feb 28, 2006 8:37 pm 
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The part number is stamped on the extractors, towards the front.

 

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Posted: Tue Feb 28, 2006 9:01 pm 
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voxace wrote:
The part number is stamped on the extractors, towards the front.


OK, will have a look ...have to get shroud out of the way first!

 

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QUARTER MILE PB: currently 14.590 @ 96.00 mph ...BOOST AHEAD!!

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Posted: Tue Feb 28, 2006 9:05 pm 
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either that or are they straight or do they look liek spaghetti?

 

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