Spine is unlikely to be his issue. If he shot a 300 grain 28" long arrow like the Gold Tip Velocity Hunter, his dynamic spine would be 0.693 so he should be using a 700 spine arrow. I put the bow in OnTarget and set it at the longest draw length that was available for that bow (25 inches) and 40lbs draw and with a 300 grain arrow he would be shooting 202.94 FPS with 27.43 Ft-Lbs of KE.
With the exact same draw length and draw weight and arrow weight, if he was using the Hoyt PowerMax, he would increase to 220.54 FPS and 32.4 Ft-lbs of KE.
Just a sample of how the speed and power can change with some different bows all using a 25" draw, 40lb draw weight and 300.3 grain arrow:
Hoyt Trykon Jr: 202.94 FPS with 27.43 Ft-Lbs of KE.
Mission Craze II: 206.44 FPS with 28.39 Ft-Lbs of KE
Bear Cruizer: 214.51 FPS with 30.65 Ft-Lbs of KE
Hoyt PowerMax: 220.54 FPS with 32.40 Ft-Lbs of KE
Mathews No-Cam HTR: 222.19 FPS with 32.89 Ft-Lbs of KE
Bowtech Legend: 224.72 FPS with 33.64 Ft-Lbs of KE
Mathews Avail: 228.38 FPS with 34.74 Ft-Lbs of KE
PSE Full Throttle: 247.07 FPS with 40.67 Ft-Lbs of KE
Now, the Trykon is both an entry level bow and also a very old design that was introduced in 2007. While it is still a functional bow, it isn't anywhere near as efficient as newer designs. The list above has other entry level bows at the top and some upper end bows at the bottom, including the Avail, which I think is a superb bow and the Full Throttle, which is the fastest bow on the market, or was if something has surpassed it (and the Full Throttle is amazingly powerful but not a pleasure to shoot like the No-Cam I put in the list which I think is the smoothest bow I have ever shot or even seen).
If you want to shoot an impala, you can probably down it. I think the Warthog is a bit tougher and according to South African regulations on bowhunting, the bow the OP has does not come even close to the requirements, which can be seen here:
http://bowhuntingsafari.com/ER_SouthAfrica.html
In essence, for small game, it requires 25 Ft-Lbs of KE and a 350 grain arrow.
For medium game (Kudu, Nyala, Warthog, Bushpig) it requires 40 Ft-Lbs of KE and a 400 grain arrow.
And for hitting the 350 grain arrow weight, I would recommend using a 150 grain broadhead to get a high FOC that will help on penetration because this is at the low end of the acceptable range.
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