Which is the real limiting factor on a stock 5.0?

[88workcar]

If you fellas want some encouragement. Listen to this. In 93 I got the "BUG" and bad. My son was 4 my daughter was just born. Money was,,,,well it wasn't. I got a set of stock heads and an intake from some one for nothing. I ported both. Cut the box open on the intake, ported, got it welded up. Ported blind (oo) when it was all done, I scraped money cutting grass to service the heads. 3 angle valve job, decked .030, new seals, .060 shims under the springs, ect... $200.00. I put it all on, the car ran WAAAYY faster. I lucked into some money got a 65mm TB. I already had 1 1/2 long tubes, 2 ch flows, 3.55s,k&n,fuel reg.,sub frames,4cyl springs all 4, muffler shop H pipe. It ran 13. 85 @ 100 before the heads and intake. 13.09 @ 105 after. Now, I gained 7 tenths, not knowing crap. All I knew was things are tight, my babies need to be fed, And we AIN'T GOT NO MONEY FOR THAT DAMM CAR. Fellas, port your stock heads. We all don't have $1000.00 alocated for alum. Have fun, do it anyway. People told me, Your waisting your time, now I'm waisting them. Who is it that said "come to the track, you might learn somthing?"