To be honest, a stockish GT with 4-branch, generic chip and cam is really good fun to rag the shit out of, and you know it'll take the abuse all day long without any trouble. If you add a tickle of nitrous, then it has the potential to be fast - at least until you empty your bottle.
Pre-throttle bodies Yoof's GT was plenty quicker than a stockish G40 with a 50bhp shot of nitrous. It did a low 15s 1/4 mile with an 80bhp shot, and had the potential to go quicker with a bit more tweaking. On the road (on gas) it was as quick as a 150bhp G40 easily - but only for a maximum of 6 minutes or so, lol.
Not quite sure what my point is - wouldn't spend thousands on a 3F engine build, but I would do the cheapish tweaks to make it a fun budget daily - and whack on a cheap nitrous kit for when I was feeling naughty. Think it puts it in perspective that Yoof likes going fast, and he ditched what was probably the fastest GT in the country for a G40 turbo conversion despite the cash, blood, sweat and tears we'd both put into the GT.