Borla Boomers are dyno- and race-proven universal mufflers for street or track, fully polished in T-304 stainless with an integrated polished tip. This Thumper version takes a 2.25in oval inlet and exits through a 4in round side outlet, using Borla's patented flow technology to add head-turning sound and a modest horsepower gain. 100% welded construction with CFF acoustic packing.
| Type | Boomer universal muffler (Thumper) |
| Inlet/Outlet | 2.25in oval inlet / 4in round side outlet |
| Tip | Integrated 4in polished tip |
| Material | T-304 stainless steel - fully polished - 100% welded |
| Part Number | 40057 |
| Warranty | Million-Mile Warranty |
Shipping: In-stock orders placed before 3 PM EST ship the same day, and everything else ships within 24 hours. Standard, expedited, and overnight options are available at checkout. Backordered items ship as soon as we get them back in stock. Contact us for lead times. See the full Shipping Policy.
Returns: 30-day returns on new, unused items in original packaging. See the full Refund Policy.
