ISR's Circuit Spec cat-back for the 1.6L NA Miata, 1989-1993. It's 2.5-inch brushed stainless piping ending in a polished muffler with a 4-inch tip — the same Circuit Spec formula as the 1.8 system, built for the early 1.6 cars instead.

Don't cross-shop this with the 1994-1997 listing: ISR sells the 1.6 and 1.8 NA exhausts as separate systems, so order the one that matches your engine. Gaskets, bolts and nuts are in the box.

• Fitment: 1989-1993 Mazda Miata (NA), 1.6L
• Cat-back system, 2.5 in brushed stainless steel piping and flanges
• Polished stainless muffler with 4 in tip
• Includes: mid pipe, muffler section, 4x 2.5 in exhaust gaskets, 6x bolts, 6x nuts