The e2 2.5 manifolds are as compromised as the e2 3.0 manifolds. I can't say they are the identical but they both have a vey sharp 90 degree elbow where the manifolds meet the front pipes.
In E3 cars, the angle is lessened somewhat and the tuned length seems to be more appropriate, as the front and rear banks on a e2 merge somwhere around the bulkhead but merge on an e3 around the end of the c pillar on a 156 - just before the fuel tank.....
All I can say is I saw a clear and distinct 10bhp gain on a e2 156 V6 on back to back runs with the oe system and a cybox cat back with a scilenced cybox decat (illegal). I am now running a GTA engine using E2 manfolds and the same E2 cybox system.
It made 280bhp (or thereabouts- several runs) at the FW on a rolling road recently BUT I think RR results are generally BS.... they can only be compared with back to back runs when changes have been made.
However having driven my 156 and my bros 147 GTA.....
Mine is quicker. No doubt about that, the 2.5 box clouds the issue somewhat.
I still think its making more power.
To change a GTA to an E2 system would involve a lot of work and it would fail an MOT.
Its not worth it IMHO and TBH........
allthough mine sounds good.......
IT realy is DUCKING LOUD.
