State of Washington stopped all emissions checks over a year ago. Reason: automobile technology has advanced, and old cars are dying out. The 94 Disco (no downstream O2 sensors) I bought with Missouri plates had small patches welded on the cats where the innards had been removed (as I later discovered). That can cause some reverberation in the cabin, so straight pipe is better. Personally, I prefer having cats in good working order.

 

What MM six points do you use for exhaust nuts?? I've already ordered the ones from Amazon and sprayed PB blaster all over/

 

You mean wrench size? I'm pretty sure it's a 13mm deep socket. Could be a 14mm. The outlet flange will be the same.. You'll need some extensions, and possibly a swivel.

 

I found some of the downpipe bolts were easier to get at from beneath, long extensions required.

 

I have found many of the motor fasteners are actually inch sizes rather than metric. Not sure about the nuts for the y-pipe connections, but 1/2 inch might fit a bit snugger than 13 mm.

 

Engine hardware is SAE because it’s 1960’s Buick. I think everything outside of the engine is metric.