ok...here's the problem...

last night, for the first time, i took my t2 out for a run just to see where my speed will top off and well, i was really disappointed...in fifth gear, it wouldn't let me go beyond 120mph @ ~5k rpm....

here's what i did....got on a lone stretch of the freeway...

then i ran it in fourth, it was pulling all the way to red line...

slowed down to about 4k rpm...upshifted to 5th gear (about 3k rpm) slowly brought it up to about 4k rpm then sped it up to 5k....it was pulling all the way until it got to 5k then it felt like i just hit a speed wall...
i checked the a/f gauge (autometer) and its showing just short of rich...but it wouldn't go any faster....

my assumption is that there's a speed limiter somewhere?? if there is, where and how do i get rid of it?

help me out here guys...

 

No US FC’s have speed limiters.
You don’t mention any mods so I assume it’s stock. I believe the top speed of the S4 was around 130mph. It doesn't take a huge drop in power to drop top speed from 130 to 120, so I’d say you’re down on power. Blocked cats and/or a tired turbo would be almost guaranteed on a 15yo car.
If it is modded, then I dunno...

 

see that's what i don't get...

here's my setup:
rb dp & presilencer with stock catbacks
j-spec s5 t2 engine with modded s4 ecu
walbro fuel pump
tb mod
tid mod
boost controller (boosting at 7 psi with an occational spike to 10)
boost gauge
a/f gauge
no air pump....i do have the ac though...