THIS. Go with Chris' advice and add 4. You will definitely notice an improvement. Also go with Giesemann bulbs, they are a little better. I believe that @Diesel can provide better info on the Giesemann's. I followed his advice and replaced the ATI with Giesemann and have seen an improvement.Personally I added 2xT5 to my it2040 leds (over a 38gl) and believe 2 more would be better.
I think you should consider hard adding 4xt5 minimum. Also factor in 2 additional just incase
2 blue plus, Aquaspecial and either purple+, or actinic