I first installed a lightened flywheel in my old SN and never noticed any difference at all, when I got my first RN, I figured a true lightweight aluminum was the way to go to get that feeling everyone talks about and so purchased and installed a TBM charging flywheel. The difference is more noticeable for sure but still very subtle.
I ran the TBM for a month or two and then swapped back to the stock flywheel and advanced my timing 3mm at the same time and the ski hit just as hard. If you are on a budget and looking for bang for the buck, the flywheel should not even be on your radar. Advance your timing 2-3mm and leave it at that.
As mentioned above already, when you get around to wondering about MSD Enhancers and such, that's where spending a little extra will net bigger gains and the EPIC is looking to be the next best mod. MSD Enhancers are a decent upgrade with more spark, slightly better timing and a higher RPM limit but don't offer the gains that the EPIC's programmable timing curves can offer.