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Brenton 86
8th July 2006, 05:11 PM
yo,
Im considering replacing my current system which is: extractors then cat then silencer then cannon, with just a straight pipe from the extractors back but im worried bout loosing power.
There is much hearsay about the importance of backpressure on NA engine but i was wondering if anyone way certain about how much is needed.
Thanks Brenton

ae86 slide
8th July 2006, 06:27 PM
your right there is alot of opinions about it,
in my experience when i removed my muffler and just used a straight 2 1/4 pipe the car felt better thats all i know.

selk
8th July 2006, 09:32 PM
less restrictive

Billzilla
9th July 2006, 12:26 AM
At lower revs you want a little restriction, as the revs build up you want less. Above about 4,000rpm I'd be wanting as little as possible.

flamingheads
9th July 2006, 11:28 AM
Talk to a few workshops about it. From what I heard if you take out all the pressure stuff and go no bigger than 2 1/4" for a stock 4ag it should be good.

DRFT - 86
9th July 2006, 01:21 PM
I run a straight through 2.25'' system on mine and it works well.......

Brenton 86
10th July 2006, 07:43 PM
At lower revs you want a little restriction, as the revs build up you want less. Above about 4,000rpm I'd be wanting as little as possible.[/b]

Thanks for the responses, Bill knows his shit, so straight threw it is http://www.ae86drivingclub.com.au/forums/emoticons/smile.gif

rthy
12th July 2006, 06:56 PM
no engine need backpressure, its all down to harmonic resonance and air speed

If you still want a cat then a metal cat is small and provides next to no restriction

DRFT - 86
12th July 2006, 07:35 PM
most likely that you dont even need to run a cat...... when I got my system done I got a call from the dude welding my pipe tang.. told me I dont need a cat... I was like man you sure my car has to go through blueslip 2moro... so I rang the dude doing my blueslip and he confirmed I didnt need a cat........

selk
12th July 2006, 08:34 PM
i just hope u dont get pulled over by the EPA

DRFT - 86
13th July 2006, 02:07 AM
If I can get a blueslip without a cat then I dont believe I will have any probs.... it was listed in the book as not requiring a cat... (car is 1983)
And I will add that the dude who did my blueslip is very strict on all things... and is as far from dodgy as you could get..

Brenton 86
13th July 2006, 04:07 PM
yea my car is pre cat convert so no probs ther

sprintrphile
15th July 2006, 01:05 AM
is 2 1/4 good for all 4age's - what is best for 20v?