Tell your mate he's completely wrong. The Pistons are slightly different but that's only the dish in them which affects compression ratio. They certainly aren't any taller.
The Block casings used in the ej255 and ej257 are exactly the same so to say one set of Pistons fit but another doesn't is complete nonsense.

My money is you've got the wrong rods.

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605whp
Quarter Mile in 10.9 seconds @ 135mph /217kph
0-100 kph 3.2 seconds

Cheers for that clarification mate! I've got the same train of thought in regards to this!


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if the rod are to long you need pistons to suite, I run longer rods with wisco pistons to off set the longer rods

Whats the part number on piston kit ?

Was deck height of assembled short checked ?

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MY99 WRX EJ2.35L 720whp 9.48@147mph
https://youtu.be/c_lYEG0_Dyo

I'm trying to get all the information together but I'm away with work atm, I'll post as soon as I have the info in front of me...

To be honest I don't think that the deck heights of the assembled short block have been measured, would you be able to educate me as to what the OEM measurements should be and what the tolerances to this are?

Piston shit: EJ257 vs EJ255 facts with pictures - NASIOC

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[I]trolololol[/I]

Have a read of this. It has all the info you need to enable you to measure it all and find out what you need to do to put right.

EJ25D w/ EJ257 Pistons Q&A ? - Subaru Impreza GC8 & RS Forum & Community: RS25.com

__________________
605whp
Quarter Mile in 10.9 seconds @ 135mph /217kph
0-100 kph 3.2 seconds

Ok I've got part numbers here now

CP Pistons part number: Sc7421
SCAT SUBARU WRX H BEAM CONRODS: SC2518020478429

Cheers I've had a read through this now and it seems as though there are no major differences that could cause the problem I'm having

Cheers I'll have a read through this