I've been through 3 of these cars now and been a member on dsmtuners for around 5 years. I have read tons of mixed reviews about that manifold. On both the 2gs i've owned they both had the stock cast manifolds and I have never had a problem. The 1g manifolds are the ones that tend to always crack. The JMfab manifold I have not heard one bad review about their new manifold they are now putting out. Alot of the members that give advice on this site ARE members/"gurus" on the dsmforums, so maybe they know what their talking about?

I would recommend just keeping your stock 2g manifold. It's probably more than enough for your goals as of now.