You are going to get different opinions on this topic, but here is mine. I have rode on the Diamond J Widening Kit for over a year, and had no issues with it what so ever. I ran raptor 660 front shocks with it, and it worked well for casual riding. I have since upgraded to +2 a arms and those perform much better than the kit. The problem with the kit is that it negatively effects the suspension geometry, which for the most part, translates to massive amounts of bump steer. As far as safety, I personally think the widening kit is safe, but some people will tell you it's not. Imo, save up for aftermarket a arms, but it's your call. I have a kit (without shock brackets) that I would be willing to sell. PM me if you are interested.
