 An H or X will quieten it down a little. I added an H pipe to my 4" "street" system and it made a noticeable difference. Made it sound better, more "even" sounding if you will. I'm not a fan of X pipes. Don't like the sound at all, but they do make more power than true duals or an H pipe.
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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