Hello Gentlemen, I am a fairly new owner of a nero 355. In my opinion the 355 is without question one of the most beautiful automobiles ever created. Then throw in the nero. Wow. Sorry Rosso people. Just an opinion. All 355s are beautiful. Now time for the 'I am an idiot' portion of my first post.. I don't understand the primary and secondary cats. This is what I think I know. I have the Hyperflow cats. I have the original 2ndary cats. Am I right in assuming the Hyperflows pass the exhaust after the bypass vales have opened under higher rpms resulting in the roar? If so then the 2ndary cats are mainly for idle? Do the bypass valves perform a perfect function and flow ALL exhaust through the hyperflows under the higher rpms? I would guess so. So my question is .. is the only reason people change the 2ndary cats is to change the idle and low rpm sound? If so, just how much can this change due to the cats? Would it be worth it to change to a Kreissig or Fabspeed 2ndary cat set up or is this just a waste of $$. BTW- I have Capriso 2 exhaust. Nothing I have ever heard sounds like the 355. Unfortunately the 360s and 430s sound like pale imitators. Again just my opinion. Thanks to anyone willing to put time into my ignorance.
The exhaust bypass opens up under wide open throttle, over 3500 rpm or so. At that point, a good portion of the exhaust is then running through the Y-pipe or "secondary cats" as you call them (could be a 50/50 split). The main cats (hyperflows in your case) are where all the exhaust runs through during idle, and during part throttle opening, the majority is still running through the main cats (hyperflows in your case). At wide open throttle, it is split, between the two.
I noticed a bit better throttle response for some reason after I installed a custom secondary bypass pipe on my car.. Now I have Hyperflows also---just waiting for the headers to get back from the ceramic coaters for installation Image Unavailable, Please Login Image Unavailable, Please Login
Well For starters........... welcome to the 'nero alleanza' ....... the exclusive fraternity of 'nero ferrari owners' ........ As f355spider said the hypers are flowing 'full time' and the secondaries flow when the 'bypass' opens. 285 what size tubes are on your new burns secondary pipe? Are you going to coat that as well?
Thanks guys for the input. That clears it up. So maybe I will do the secondary bypass upgrade. This gives me a chance to tinker with an otherwise perfect machine. I have the fabspeed headers as well. The person who owned this car before me has done just about every upgrade possible so this doesn't leave much for me to do other than just drive it.
