20g,ej257,sti 3heads,wiseco pistons. Is a true 3 inch exhaust a must ?
18 March 2009, 06:59 PM
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20g,ej257,sti 3heads,wiseco pistons. Is a true 3 inch exhaust a must ?
As above really with my spec would you advise a true 3 inch exhaust system to get the best out of the set up or would a 3 inch down pipe and 2.5inch mid and rear box be ok?
18 March 2009, 10:32 PM
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Well I'm on a forged bottom end and STi3/4 heads with a 16G and FMIC, and I get compressor surge around 3500-4000 rpm. Admittedly I need a map tweak but I guess the exhaust could do with freeing up a little. I run a 3" sports cat which goes to a 2.5" system the rest of the way.
18 March 2009, 10:43 PM
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I've run mine to 1 bar so far and all is good . Knock is low and fueling seems spot on on the A/F gauge .Ran the engine before on a 18g with no problems surge wise at 1.5 bar but had pre 96 wrx heads as well . What boost you running when surge occurs?
Last edited by l70byb.; 18 March 2009 at 10:58 PM.
22 March 2009, 07:57 PM
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Well I've still not checked, but it's at less than 1 bar basically. Following the remap at Zen it's now making 346bhp on a 16G with forged CDB and mildly worked STi4 heads, Harvey headers and up-pipe, sports cat and 2.5" system. So a 3" system not necessary at this power level.
Last edited by silent running; 22 March 2009 at 08:09 PM.
