Dont have any personal experience with either but I havent heard one complaint about the accufab plenum/throttle body combo. Seems to make decent gains, but it looks like the money is better spent elsewhere on an NA car. On the topic of shifters, I hear that any aftermarket is better than stock. The pro 5.0 is a racier feeling shifter and is shorter than the Steeda tri-ax. It is about a 50/50 split on peoples opinions of the shifters so I would say drive 2 cars with both shifters. Then you can decide.
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.
I got the Accufab combo kit on my car last week , you can read more is you clic here !
I had a idle issue and some weird exhaust sond when I was downshifting ( slowning down ) and I realized that my EGR valve wasn't tighten so I don't know if it did affect my dyno numbers , I'll redyno it next week just to see !