Here's what is recommended:

HT-IR-ID-BFB-DiS-PS-CT-Jump-PH-Sweep-TT-(Spineshatter)-VT-LS-FT(DF)

That's how you should do your burst. If you're not breaking 300, then you're doing something terribly wrong somewhere. You're doing the optimal rotation of H-IDC-P-TTT, H-TTT-P-IDC-H-TTT-P-IDC, so the only thing I can really say is that you're just not being quick enough with your skills, or thinking too much about the rotation, thus breaking the fluidity. With i90 on a dummy you should be 330 stable-ish.

Save your jumps for your bursts, or your friend isn't "testing" you properly.