Here's a few suggestions.
1. Pipe OD and hose ID need to be completely clean. Like brake cleaner clean. I've seen people use hairspray to make it tacky as well, but I've never had to go to this extent.
2. T-bolt clamps are not necessarily the best in every application. Good quality worm drive clamps work well too.
3. Sometimes you can deform the pipe if you go too tight with a t-bolt.
4. I assume the pipes have beads?
5. Lugging wot @ low rpm makes this happen more.
Thanks for the pointers, its the 90degree hoses that go from the top of the intercooler onto the inlet on the front of the motor.
