I was looking through the archives because I am wanting to put a full custom exhaust on my euro 86 420SE. I want a little more performance (as much as I can get obviously), but I don't want a big increase in sound, esp. interior resonance. I use this thing as a highway cruiser, so int. sound will get real old real fast!! So this is what I am wanting to do as of now...any input is appreciated. I got some true dual manifolds off a euro 500SE, and I am going to use Timevalve downpipes, and then have a full 2" or 2.5" (?) stainless exhaust bent, leaving out the cat and the center kidney mufflers completely, but leaving the stock rear muffler. I don't know, but I am hoping that this will increase sound a little, but not much, and still flow decently well or a lot better than stock at least. If I did use this setup, would I have to put an H or an X in it where the cat is now, and where would I put the O2 sensor? Thanks for any advice.

Yes, definately put an X or H pipe in the system just behind the tailshaft of the transmission. Also, include a port for the O2 sensor by the passenger downpipe. This is necessary for the CIS system to modulate the EHA on the fuel distributor.

The system should sound very nice.