This is always a little complicated because there are so many conditions its tough to generalize everything. In general I would say the inserts that come stock with the Goose Bumps, the standard open cell type insert, gives the most traction and keeps tire wear to a minimum. These are probably the best inserts to run on the 2wd SCT trucks for the majority of the conditions since 2wd's tend to be a little on the loose side.
If the traction starts to build where there are blue groove sections and generally feels grippy than going to harder inserts can improve the performance, give more forward bite and provide more stability when entering high-speed turns. Remember that typically going harder on insert also means more tire wear and especially when the track has grooved or has rubber based traction. The molded inserts are also going to change the profile of the tire and that will also play a role in the performance change.
I attended a race recently where the top 2 trucks were on Goose Bumps. One driver was running the stock inserts and the other on molded inserts. The track had mixed conditions but the truck with the harder (molded) inserts was a little quicker and looked a little more responsive on the portion of the track with a slight groove on it. With 17.5 or stock power in the trucks I didn’t see either truck with a clear advantage overall, with the mixed conditions.
I would tend to run the stock inserts until the vehicle has pretty comfortable traction then I would start looking at options to improve stability and predictability. It's also important to remember that if you are running 4wd SCT the vehicle is much heavier and can support a harder insert much sooner in conditions than a 2wd. I would tend to run molded or harder inserts in 4wd much sooner than 2wd.
Please remember that over-time all the inserts soften up and this is a factor as well. The constant pounding on the jumps, surface, washing them or applying tire traction all deteriorates the insert and can cause some adverse affects.
We are going to continue to offer the Goose Bumps with the standard insert but will also offer a molded option in the near future specifically designed for our tire bodies.
In the time being I have seen guys use AKA 1/8th buggy inserts in the Goose Bumps with good results as well as the PL V3 molded and closed cell inserts. The reason these inserts were used because they were the widest ones available and the SCT tires need the extra width. None of them are the perfect match because they aren’t exactly designed for that purpose but will get you by in a pinch.
Hopefully this helps.
