will that mess my computer up and service engine soon light on and a off road y pipe through a cat bypass wit a loud mouth good idea or no!

 

When you eliminate the rear O2s, you will either need to get it tuned out or run o2 simulators to avoid getting an SES light.

 

and you will see minimal gains by doing the orp.

the stock setup isn't all that restrictive...least not when you still have the stock manifolds.

but it WILL be louder without the cats.

i say save the $$ and put it towards headers later on.

 

Yeah, save for headers. ORYP+LM is cool for breaking noise ordinances - almost to the point of making your 'bark' bigger than your 'bite'. You won't see more than ~5hp or so realisticly.

 

That's debateable. With lid, ORY, Loudmouth, and the free mods I ran 108mph in the summer heat and 110 mph in the cool fall air at the 1/4 mile track with an automatic trans.

Totally stock it ran 105+ in the heat and 107 in the cold air. So the lid, ORY, and Loudmouth got me 30 hp.

 

And I would still give 5hp or so credit to the ORYP and claim the majority of that 30hp came from your lid, LM, and what not.

 

But how do you know that? I've never seen anyone dyno just changing to an ORY. Could be 7.5 hp from the ORY or maybe 10hp.
Not picking at you, but at the way the internet tries to turn rumor or guestimates into fact.
Another one is people claiming huge gains going to true duals on a bolt-on car. I went from a 2 1/2" Y-pipe into a full 3" catback with a Dynomax bullet to a full 3 inch true duals into bullets dumped just before the axle on a full heads/cam car and gained very little at the track.

 

Al - I'm speaking from some of my experiences. I too went from a stock, catted y-pipe to an ORYP with stock manifolds on two different LS1 cars. On both cars, it didn't do jack for my track times/mph. Others have posted efforts on a dyno where a catted y setup only restricted 3 or 4 hp vs. the run they just made with the pre-cat cutouts open. So, I have faith in my guess-timate.

As for the duals...I ran consistently .2 tenths slower after I switched from 3-inch duals back to a Magnaflow (because I was showing up to work with headaches ).

It's not my intention to post on here as if my word was the end-all be-all of a discussion. I only offer up my experiences for people to interpret within a greater, collective data set.

 

Have a Mac ypipe (no cats) and O2 sims in very good condition?????

In 98 and 99 the cats were more constrictive than '00+. If you see a the ypipe and stock pipe side by side there has to be a nice gain there. It looks (is) much bigger with no flat spot on the drivers side. Installed on jack stands, wasn't bad.

When I did H/C went to headers.

Oh, It will make it louder.