I have backfired mine after I had the Bob George made blow off valves on and they worked. I have also seen guys with the Wilson valves backfire and they also work well. And yes the top bolts are short and I replaced all of mine with longer ones. Indy always told me there was no issue with these intakes but said the short bolts are a safeguard in case it did happen The epoxy inserts from Indy also help with the puddling of fuel and I did install them too. If you want I can get a pic of what they look like intsalled.

Just seems like with the big plenum volume backfires will happen and even more so when cold starting. I knew there was always a chance on start up but my 2nd blowup was while driving through the pits so that was different.

Russ