kusee pee

So both mufflers bypassed is the maximum noise option then? Cheers!

agentpennypacker

Yes, of course! Too loud for some tracks though : (

Colin 90 C2

I'm using a Fuchs (the people that made the earlier wheels) cat bypass. I think I must be the only one.
When the 964 was new, I think the set ( cat bypass, secondary bypass and tip) was $1000 to $1200. Really great quality. May be up for sale shortly, along with a gemballa priamry muffler.

agentpennypacker

Sorry to bring this one back, but all the bolts are coming off fine except for the 02 sensor. Did you guys use vice grips and a hammer to get it going? Not sure which way to go...

garrett376

I just tried cat bypass, primary bypass, and secondary bypass - it louder than a @#(*$&!!! Way too loud for even trying to show your friends in the garage! I drove up and down the street and every neighbor came out to see what the commotion was about! I'll use it on the track, but no way it can work on the street without earplugs!

Chris, for the O2 sensor, I use a large crescent wrench with a long handle. I've never had any trouble removing the sensor... but then again there's no salt/snow out here.

dfinnegan

My O2 sensor came out with a large wrench, but it nearly didn't. In the end it left a good deal of thread behind. Some I managed to get out, but the rest required a re-tap. Ultimately the cat held up and I was able to put a new O2 sensor in.

agentpennypacker

I found some O2 sensors for $50 or so. I have it out now (large bolt in it's place - 3/4"), but will order one this week. The car is running fine, but definitely a little rich

I did have a little trouble getting the cat bypass to the cup bypass. I wedged a wrench between the bumper and the cup bypass to get them closer together, but I am still getting a little air where they join. Any suggestions?

dfinnegan

I've seen several posts here stating that the lower priced O2 sensors are often of lesser quality and give problems when wet.

Marc Shaw

I don't think that cheaper ones are sealed from moisture well - I think that only real Bosch are recommended.

Marc