help, help, help... decision has to be made by tonight

hey everyone, im replacing hte intake gasket on my dads 7 and had a few questions. i also have an rx7 (but mine has an engine fire and im in the process of installing a 20b) anyway... there was a DP on the engine that was in my car so i have a free DP. can you tell me the advantages/disadvantages of running a downpipe (I live in CA!)? would i have to remove hte airpump? my dad isnt one for mods and the car is completely stock besides a k&n filter in the stock box, and an efini y-pipe. would this change the exhaust note much? how much extra HP would i expect?? basically its a weekend car which we share, but he likes it how it is and i wouldnt mind a little more power if its not a big deal.


PS how do you remove the stock precat? i cant seem to see any bolts... everything looks to be covered by heatshielding

 

You will save on weight when removing the pre-cat and using a DP. It will also help the turbos to spool up faster due to less restriction to the exhaust flow. Not to mention that more of the exhaust heat will pass down the pipe than with the pre-cat. Try using header wrap on the downpipe also.
I don't think it changes the exhaust note very much and you would probably free up at least 10 - 15 hp.
Remove the heat shield (2 bolts) and the pre-cat is held on by four nuts.

 

What he said.

 

There are no advantages, only disadvantages. Get a downpipe.

 

sweetl, thanks very much! oh, about emmissions (since i live in CA) do you think ill have a problem cause there horrible here, and im doing the intake gasket so it will FINALLY pass smog!

also, do i need to remove the air-pump? it pumps to hte precat right....

PS where is a good place to get hte header wrap quickly (probably not kragen huh?)...id need to get it tomorow morning

 

PPS i have no idea what brand it is, but it looks like 3"... area all DP's about equal?

 

More or less, performance-wise. Best to have stainless steel as it doesn't rust.

 

The DP is only effective until the cat is warmed up. Once the cat is warm, the DP is only a restriction. Not sure about the visual inspection in Cali, but just make sure you've taken the car for a little ride before testing to get everything nice and warm and it'll pass no problem.

 

I pass my emission with my 3 in. downpipe on. in california. I think you should be alright. Just warm up the car before the test! The air-pump does not need to come off. Trust me you should be alright.

 

where can i get header wrapping tape from???