Same thing happened to me. I got them rebuilt by top end performance and as soon as I got them running they would randomly spit fire out the air horns. Never figured out why, and it eventually happened less and less as I got more miles on the engine.
I believe I got my carbs for $650 with everything, but after the rebuild, ITG filters, air horns, heat shield, I was at around $1500 also.
Triples just look right in the bay of an s30 and the sound is intoxicating