Guys 98dB Is not too bad, My exhaust is about 112dB at 4750rpm! It hits a bit of a strange tone around there and the noise output jumps up! lol..
Check out these video's of my car for some idea of dB.
The first is my 5ZIgen which was tested at 93-94dB at most tracks I have been on. (much nicer sound than my current set up )
The next is 3.5" down pipes (big bore de-cats) with the 5Zigen rear cans on a custom 2.5" true dual.
cold idle.
4.75K RPM Track test rev's
Its about 95-96dB at 4K tested at TOTB last month, I still need some extra silencers as it fails most strict track day noise limits!