Very disappointing low dyno numbers please help!!!!!!!

zuperman 370

Hello fellow forum members so today I went to get my car dynoed, before I tell you guys what happened I'll start of by telling you about my base numbers and my car, I have an AT 2009, I dynoed it when it was bone stock last year using a dyno jet, the numbers that I got where 266.91hp and 227.72tq and the car was very rich from the factory, now our fuel isn't the best quality they claim it's 91 but everyone says that it's less, so that's why I assumed that I got lower numbers when comparing to other 370's.

Exactly one year to the day, I got my car dynoed again on the same dyno jet that I dynoed my car on, same time of year same weather conditions and the car was cooled down and everything, the mods that I have are follows, amuse stti exhaust motordyne xyz pipe resonated, F.I long tube headers, top secret intake, of course the car is not tuned yet, I was hoping for at least 280-290 hp, well when I dynoed it I was extremely shocked to say the least, numbers were 274.05hp and 233.31tq, and the AFR was a tiny bit richer with these mods on. So with these mods I got a 8hp increase and 6tq increase :s of course at this point I was furious, a lot of thoughts went through my head I though ok maybe the guys dyno is screwed up and gave me low numbers, but even though that was the case, I had the old numbers from last year to compare with so even if his dyno is screwed well I can compare it to the last time. Another though was that I might need a tune, but gains that I will get from a tune are 10-15 hp, so that will leave me at almost 290 ish, and that's if I'm lucky enough, which is still disappointing given the mods that I have, I'm really lost guys and don't know what the problem might me or why I got these extremely low disappointing numbers, I have seen cars on this forum get 277 bone stock, please every one chime in, tuners non tuners plz I need ever ones advice on this, I'm going to get the jun cams now, but after seeing those numbers I feel so upset that I don't even know if I'll get them now, what could be the problem.

P.S I got these two dyno readings in the 4th gear, pleeeeeeease advise me on what the problem might be, any input at all could help me.

P.P.S weather condition was really good, very low humidity and nice cool breezy weather of 20c.