Quite soon after I installed an OBX 4-2-1 header (pictures 1. and 2.) on my 1990 Miata I realised that my custom 2-1/4" exhaust system was going to have to go away.  It had begun life as a Pacesetter Monza catback (I paid $119 over a year ago) that was far too loud for my taste.  I added an 18" glasspack to the mid-pipe that toned it down, but the biggest problem was the pressed and crimped together muffler that rattled itself apart every 2500-3000 miles.  I had it off at least 4 times to cut open the muffler can and weld the baffles and inner pipes.

At least I got so good at dropping the catback that when I recently got my OBX stainless steel system (pics 3., 4., 5., and 6. -- from eBay, $245 delivered) it only took 45 minutes or so to take the P.O.S. off and install the OBX system.

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5.
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Picture 4, shows the OBX catback system as received (YES, it really is that shiny!).  It has an oxygen sensor bung at the forward end of the mid-pipe to accommodate the OBDII '94+ models that has to be plugged for the '90 to '93 NAs.  Picture 5. shows the plug I machined from aluminum in my "little machine shop" as my wife calls it--I understand that most muffler shops stock these plugs, it's an 18 mm x 1.5 mm thread.

Photo 6. is a view up and under from the rear showing the installed system, picture 7. shows how it looks to the rest of the world when the lights turn green.

This system is great, it is well designed and constructed, the welds are top notch in appearance and penetration (see photos 8. and 9.).  I was particularly impressed with the triangulation on the forward mid-pipe hanger arm shown in photo 7.  This is something they didn't have to do that indicates a desire to make the product as the best it can be.  It's sound is slightly louder than stock, with a very low rumble at idle and when taking off.  There is no drone at any of the usual higher RPMs (3K and 4K) and it supplies an authoritative bark on heavy acceleration and WOT.

Highly Recommended!!!

Gary at TDR was great about this and sent me another blanket with no hassle, however the damage to the header had been done and 400 or so miles later the #2 tube let go and blew a hole in the new header blanket. As I now had an immediate need for a header I ordered the Jackson Racing ceramic coated 4-2-1 unit from Moss Motors (it was on sale for $349 at the time). This is a real ceramic coated header as opposed to a ceramic painted assembly like the OBX, the ceramic is a bona fide high performance baked on coating that does a completely counter-intuitive job of reducing heat radiation from the header!

The TDR blanket did not go back on, as far as I am concerned the jury is out on this thing--we'll see what happens when more people have to take them off. I have been criticized by some that I did not properly mount the blanket, or that I wrapped it too tightly around the header--neither of these arguments has merit. I mounted it in complete accord with the supplied instructions, and ensured that there was an airspace between it and the header; however as stated above with gravity and vibration being what they are it did sag into intimate contact with the header.

The good news is that I got the OBX header repaired for $50 at a speed shop in Daytona and it continues to serve Miatadom in my brother's '93.