Well, true not the best first mod, but when you do swap out the plenum and TB, I'd highly recommend the Accufab pieces - high quality billet aluminum TB and the plenum is well engineered and beautiful. If funds are a little tight, the C&L plenum would be choice #2. But expect only 5-8 RWHP with either combo.
Both the Tri-Ax and the Pro-5.0 are well built. My personal preference is the Pro-5.0.