Love my Kooks muffs on my street strip car. Car runs same numbers with or without. Polished stainless, sound great, great looking
Mine are 3 inch
They make a 3.5 in and out
Part umber is R35-35-10

69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8