Which upgrade yields the best results?
 

Which modification would yield the best results in a Mazda 3s with a CAI and custom catback exhaust? A lightweight flywheel or an underdrive power pulley kit? And is it a must to replace the stock clutch if upgrading the flywheel?

If I were to replace the clutch I would use Mazdaspeed's sport clutch upgrade which provides a 30% increase in clamp load:
( http://www.mazdausa.com/MusaWeb/spee...ode=MZ3&bhcp=1 )


For the flywheel I have been looking at SRMotorsports' 9.25 pound aluminum flywheel:
( http://srmotorsports.com/Mazda3_Perf...Flywheels.html )


SRMotorsports' underdrive power pulley kit with 15% reduced diameter and 400% lighter than stock (2.1 lb. vs. 8.2 lb. stock):
( http://srmotorsports.com/Mazda3_Perf...r_Pulleys.html )

flywhell would prpduce more gain and no you don't need to replace the clutch unless you plan on pounding on the clutch pretty hard or adding FI.

I'd contact Ken @ www.mazda3online.com He's got the MS clutch and flywheel for the 3. Save you a lot of money.

anyone have an aftermarket flywheel installed on their mazda 3?

be sure to shoot me an email or PM on any aftermarket or performance part you need for the 3

My understanding is that lighter flywheel will make your car less streetable. I don't think of these cars to be sport cars to put light flywheels. I used to have an 1994 RX7 when I lived in CA and thats the kind of car you want to put lighter flywheel, for track.

YRMV, but i have a '96 Accord with a 8 lb Fidanza Flywheel and it's perfectly streetable. builds and looses revs faster than stock, less wieght= less inertia so it is easier to stall but not hard to drive at all.