I can answer this question for you, I just sold my 90' Formula 350(L-98) I took the cats off about 5 yrs ago, it did not hurt, it helped, it got me into the 13's, best ET before the motor work with bolt-ons, stock converter and 327 gears was 13.41 @ 102MPH! it did not cause EGR problems, but after I built it the motor to a 355, ported heads, ZZ-9(520 lift)cam, I got the code 33 a lot, changed the EGR and still got it! a cam could cause a code 33, but the cats off should not, but then every car is different, my car was speed density.
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98'Trans Am LS1 273 gears Whisper lid,K&N,Whisper MAF ends,Flowmaster,Best ET on street tires 13.17 @ 106.49mph