Here's the review I've been meaning to post up for a while...
Late last year, I needed to change my clutch. So while I was at it, I did some modding to my drivetrain:
1. Lightweight flywheel (custom ground)
2. Exedy heavy duty clutch
3. DC5R LSD
4. J's Racing 5.1 final drive
The following is only my subjective feelings about these mods, I have not dynoed nor tracked my car since the mods.
The heavy duty clutch and flywheel combo works well but the clutch can be quite "sticky" meaning a smooth 1st gear launch is not easy without piling on some revs (~2000rpm). Below that, there is quite a shudder. In terms of acceleration, it's hard to tell as I changed my final drive at the same time (which in my opinion, does more than the flywheel in regards to acceleration).
The LSD is definately a good mod. Before it, there's this uneven right hand bend that I would accelerate hard through, and all I would get is understeer and wheelspin. Now, I can power through like a champ. The difference is quite dramatic in such circumstances where an LSD is useful. With normal everyday driving however, the presence of the LSD cannot be felt, and its usefulness under normal driving is questionable (yes, it's quite effective in the wet as well, but ultimately on the street, the tyres you have is of utmost importance).
The final drive gear set... probably has made the most acceleration difference in view of the other mods. It quite simply allows me to rev to the redline really quickly. But of course, with the change of the ratios, my top gear speeds have also changed. 1st redlines ~50kmh, 2nd redlines ~88kmh, 3rd... I haven't tried. What it does mean is that to get to 100kmh, I have to change to third gear - losing some precious time whereas a stock Euro can get to 100kmh in second. So getting to 100kmh to me seems quite similar to a stock Euro due to the gearchange, if only slightly faster. But I would be surprised if I haven't reduced my 0-400m times. Another thing to note is that my speedo is out of whack. My GPS would tell me I'm doing 110kmh, but my speedo would be showing 130kmh! My mech said its due to where the speed sensor is in the transmission and is due to the change of my final drive. So I have to be extra careful... AND I am racking up my odo faster than it ought to!
In summary, I am happy with the mods, considering I have no other performance mods whatsoever (eg no I/H/E).