Arrow Question for new bow

[cuboodle]

I shot a hoyt buffalo 45# at 28 I shoot 3 under.  I got a new bow in the mail today a helms deep 44# tillered for 3 under  by Mr. Gregg Coffey I thought the same arrows would be close.. Here's the deal poor arrow fight whip to the left. Im shooting full length easton trad only 400's and GT traditionals 35-55 50 gr insert and 125 tips same arrow flight, I switch to woodies spined 50-55 same arrow flight now here is the question,  Why when I switch to split finger do all the above arrows fly like darts?  Im guessing underspined with three under?  Maybe Ill start trimming tommorrow