I've had both a type 4 and bpipe. here are my thoughts:
T4 had way more punch. My 98 was completely stock except choke removed, & skat trak 14/18 prop and the T4 with water injection. The T4 made it rip. Most people who rode my ski didn't like the way it jerked (like turing on a light switch) and took off (aka arm rip). It was more difficult to install. I surf ride and loved it. It sounds 100% more brappy than a bpipe
You do need to check and maintain a T4. The water injection nozzle plugged up the pipe ran hotter than normal and the coupler burnned. Jetski sloutions has an update and modification for this pipe. Used, it will cost less than a bpipe so IMHO its a better bang for the buck.
The bpipe is simple to install is very low maitenace. You do have to watch it doesn't melt your gas tank. It will fill up the waterbox with water at idle and stall easier than the T4, so you need flow control valve. It is smoother on the throttle response (aka more linear).
I really like the snap of a T4...stock with MSD (which I didn't have) I hear is the bomb! I have a head, air filters with the bpipe it's much smoother with 98% of the punch. So in summarry the bpipe is a more comfortable ride and lower maintainace. T4 get that yank and haul ass snap I love!