murrayg

I’ve been running my 85 NA with a header, glasspack muffler (in place of cat) and stock muffler. No "sniffing" in Nova Scotia, so I don't need the cat. The sound is “just” OK. Still a bit raspier than I like, but the best option so far. However, I’m still willing to try a couple of more configurations. I’m going to replace the stock muffler with a FlowMaster 50. I ran this configuration with a FlowMaster 40 a while ago and it was way too loud. Also I’m willing to try the cat again instead of the glasspack muffler. My question: How restrictive is the factory cat assuming it’s in good shape??

Thanks for all the help, I’ll post my results when I’m done.

Gord.

El Commandante

you lose about 10 hp, so pretty restrictive. Run a generic high flow cat. You can find them on ebay for around 50 usd.

murrayg

10 hp!!?? This surprises me. I didn't think you could do anything to an NA to get 10 easy HP.

knfeparty

All the power gain is at the top of the power band. Guys who run wide-open on the track notice it. I think driving on the street you won't notice it really.

ritzblitz

I highly doubt it is a 10hp difference. Maybe 10 at the crank...

Install a resonator. Switching mufflers probably wont help much with raspiness.

p_tothe_g

I am currently running 2.5" tube with a dynomax race bullet in place of the cat and a flowmaster 40 for a box on an S2. Sounds awesome until you hit about 4000 rpm, then it sounds like hell. Going to frankenstein a new system later this summer using a magnaflow cat and box. Might keep the race bullet to run post cat, but we'll see. Even though it will be the second exhaust I'll be making for this car, still spending less money than for any single after market exhaust. why hasn't any after market co stepped up with a quality system for these cars? heck, there has got to be about 30 different options for 911's

Eastep

Im running stock header, cat delete (replaced with stainless res) into custom 2.5 catback, ending in a AMG styled glass pack type muffler. sounds ok. its loud outside (from what im told) its only slightly louder then stock inside. Im not crazy over the tone of the rear muffler, so im gonna swap it for an ANSA rear can. I can feel the added high RPM pull with this system