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					Originally Posted by Hasbro  I'll put this here instead of a new thread as it is somewhat applicable. Care to comment on my plans on a 2.5 base? I'm thinking maybe +10 whp?
 - Underdrive pully - check.
 
 - Lightened flywheel/clutch? - In a nutshell, Raby said the 2.5 could handle this the best. Is there such a thing as a lightened dual mass flywheel?
 
 - Weight loss- -367 lbs. (2,455) so far. Goal around 2,350, including weight added back on (structural stiffening and body work/aero).
 
 - TB, software?, exhaust (headers, 2 cats, no mufflers (for weight loss) - still need the headers. Will I need 2.5 specific headers?  Would Pedro's system work adequately with the semi-custom software? Alternatives; rolling dyno plus? I'm looking for a broad range torque improvement, not 6700 rpm hp. This is more of an auto-x/street car than track - built for fun and don't care about being class competitive.
 
 - Manual steering.
 
 - Re-working of body/drag but I'll leave this alone for now but it will reduce the hp required to go x mph.
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Weight loss and UD pulley are a slam dunk.  Intake/exhaust/DME software are a moving target and best done together with a custom dyno tune.  I don't see much benefit in any off-the-shelf flash unless it gets further tuned to your specific car and mods.  Everything needs to work well together and then you can find some hidden HP.
A lightweight flywheel was on my brother's 2.5L car while mine retained the dual mass.  It definitely spooled up faster and was a little quirkier to drive around town.  We never dyno'd B/A this change and we noticed no difference in lap times.  He was usually a bit quicker on tight tracks and I was quicker on more open tracks, always within a few tenths. 
The only benefit to me for manual steering is a little weight loss.  The PS pump is very reliable once the UD pulley is installed.
Good luck and test/verify as you go!