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is it worth puttung a 2.5" exhaust on 4.2 efi
Posted: Wed Oct 14, 2009 11:36 pm
by MUNGA GQ
is it worth puttung a 2.5" exhaust on 4.2 efi. Welding a pipe straight through the cat and fitting 2 new hi flow mufflers ?
Now the floor on the pasagers side heats up a lot, and i was thinking the cat may be blocked and over heating it as well as heating up the floor.
Any help.
Posted: Thu Oct 15, 2009 6:48 pm
by 76patrol
bud a bigger exhaust is always a worthy mod. i'd go a 3" myself. on my 3l i run a 2.5". no cat just a straight thru muffler and dump pipe. prob should have a cat though. haha just my opinion. cheers ray
Posted: Thu Oct 15, 2009 7:16 pm
by BigrigCQ
I ran 3" too extravagant used to much fuel and too noisy!
Went back to 2 1/2 and got better fuel economy and heaps more torque bak when towing the boat!
Ditch the cat!
I only run 1 hooker 2 1/2 muffler with dumped before diff!
Posted: Thu Oct 15, 2009 7:25 pm
by 76patrol
i hadn't even considered fuel. listen to bigrig i reckon. bigrig im with ya on the donkeys. 3 truck will be interesting again.
Posted: Thu Oct 15, 2009 8:35 pm
by GAS-747
You want some back pressure to produce power.
Non turbo I would look at 2.5, and for turbo 3" JMO...
Posted: Thu Oct 15, 2009 9:32 pm
by PGS 4WD
The bigger exhaust is better however it also means devation from stock and therefore the stock tune may be an issue, large modifications from stock can present less benefit than expected due to them not suiting the standard tune. Larger gains are often acheived by the tuning process than the mechanical change.
Joel
Posted: Thu Oct 15, 2009 10:28 pm
by wilsy
PGS 4WD wrote:The bigger exhaust is better however it also means devation from stock and therefore the stock tune may be an issue, large modifications from stock can present less benefit than expected due to them not suiting the standard tune. Larger gains are often acheived by the tuning process than the mechanical change.
Joel
Joel, so what mods would you recommend to a 4.2efi, already with extractors and 2.5"exhaust, for those of us wanting a power upgrade without the use of forced induction??
Posted: Fri Oct 16, 2009 6:55 am
by create
I installed a 2.5' mandrel bent system with 3-2-1 extractors. I went for straight through no muffers or cat. It was far too noisey and attracted too much attention. It popped and banged and droned really badly. I have now put a redback hi-flo muffler and its much better. Well worth the change.
Posted: Sat Oct 17, 2009 12:37 am
by BigrigCQ
bigrig im with ya on the donkeys. 3 truck will be interesting again
Bloody oath the 3 car is going to be very interesting!
The donkees have got a real good crew this year!
If they dont right off there vehicles at tamworth!
Stay only with 2 1/2! you will regret going to 3"
Posted: Sun Oct 18, 2009 4:34 pm
by MUNGA GQ
thanks guys i will be going for a 2 1/5 inch.