me and my brother were among the first 3 or 4 people on HQ to have rocket pipes. we got our sets at the same time, sometime back in 2003 or 2004 i think. at that time, they were pretty new.
since then the silencer design has changed for sure. its a lot cleaner looking now. i actually upgraded to the newer silencers at one point in time.
i bought them originally for a 4mm passion motor. of course, i ditched that junk not long after i got it for a good running 4mm stock cylinder motor. they made more power on that motor than cpi, despite what the builder said.
after that i got a 4mm cub motor. power delivery was great. i won tons of hillclimbs with that setup.
next up was the 10mm motor. they did run well on the 10mm cub, but a little restrictive. thats when i upgraded to a big bore shearer.
i would say the 421 cub is about the cut off as far as gaining performance goes on the bigger motors. anything 421 and smaller, the rockets will be a great addition to. again, you can run them on the bigger motors, but you will sacrifice a little top end.
all that said, $600 for a set of these pipes is not out of line. i feel they are superior to the cpi. one reason people talk down on them is because they dont know shit about them. theyve heard the horror stories of the company being passed from person to person. in fact, the rockets are an almost exact replica of the GRR out frame drag pipes. i bought a set of GRR outframes a few years back to look at the similarities. they are in fact the same pipe. i dont know the whole story, but what i can gather from all of the different rocket builders is that the rocket pipe design was stolen and put into production. take it or leave it because at this point in time, who the fuck knows.
all i do know for a FACT is that these are great pipes for almost any motor setup. between me and my brother, we have run them on the following motors with great results.
4mm stock cylinder drag setup
4mm woods port from FAST
4mm cub motors
10mm cub motor