Use it for the first time 2 weeks ago, have had it for 3 yrs. 4" with dynomax bullets. I was useing it while testing my throttle stop so I dont have an all out 1/4 comparisons. It did raise the EGT up around 100* or so. I had even rejetted thining I had made enough adjustments. It went 10.901 @ 138. I think that it would run as good, or even better with these on in the 1/4. I just dont like mufflers. I like noise. But I will use them for the division race.