For the record, I've never found enough gunk anywhere in my engine internals to ever disrupt flow or performance. Not even in the cylinder heads.

I doubt seriously that you'd see a remarkable improvement, if any, but at the same time, it can't hurt if you follow the instructions.

I'll second that. My Series 2 has about 150,000 miles on it with no performance issues, and my '93 had over 220,000 miles on it and ran like a champ.

Actually, if you leave those types of cleaners out of the equation, and at 150,000 miles plus took apart the engine, most are extremely surprised at how clean the engine is. The valves usually have little to no buildup at high miles, and if the valves have no buildup, nothing else will.

Now, if you're one to run on empty all the time, with the fuel level always low in your fuel tank, then I might be worried that the injectors might be starting to build up some gunk there, but only with what could pass through the fuel filter. But only if you've had to replace the fuel filter more than twice, and again, only at high miles.

i dont know, i mean im not saying that the car doesnt run well, its just that at times it feels very sluggish as if there is something going on, i dont know if this is normal, but i mean somedays it has that extra pep and somedays it just doesnt lol..its like a human, somedays its tired somedays its full of energy lol..what do u think the problem could be?

i wouldnt be surprised if the cat is in pretty bad shape (clogged) but thats something thats going to be changed very soon so im not concerned too much about that...what about 02 sensors? ive been skimming some forums on here and some people seem to believe that even if the sensors arent throwing codes they could be bad and throwing the A/F ratio off..could this be something else to look into?

I think every car is like that, a lot of it has to do with things like temperature and humidity, heck are sure there are other things that affect it too. But I know my car is the same way, as was my Bonneville back in the day.

This doesnt even take into account the presence of gremlins either, we cant forget them.

Usually a bad O2 sensor is the culprit for clogging your cat by making the engine run too rich.

Also, as for some day running peppy, and some days not as much: Everyone'* car does that. On my car, the supercharger LOVES cold air and makes the engine run like the bad outta hell on cold days. On hot days, not so much so, as heat makes alot of difference not only on supercharged cars, but also the naturally aspirated ones as well.

yeah thats def true, temp makes a big difference for sure, i can def tell that..so when i handle the exhaust and change my cat, how would i know its "clogged" and if the old ones pretty bad, would u reccomend changing the 02 sensors?