From what I know about botom fed attties the decent ones will cost as much or more than the Terminator Mod your looking at, the attie that comes with that mod got good reviews and was made for it and may be the best for it, maybe your willing to spend the money on a topper then Id suggest an RM7 (Rogue) thats what I just got last week from REO's MODS and I like it alot, dual coiled, top side air fed, easy to build