No, if you replace your downpipe your original cat-back system is still on the car. If you keep the original cat-back system and replace your downpipe then you still will get some gains in horsepower, however the gains will not be as good as they would with an aftermarket cat-back system and downpipe.

 

that isnt always true there are DPs that bypass the cat other wise I have Megan DP and test pipe. so with Megan needs a Hi flow or test pipe.

I wouldnt run the stock cat on the 3 inch exhaust though aleast by a hi flow or the cali ralli cat

 

Okay, what about regular maintenance on my Evo 9? From what I've gathered Mobil 1 Synthetic 5-30w is the best oil to use but what about the oil filter? Should I go to the dealer and buy their filter or should I just get one from my local autoparts store?

 

I just get mobile 1 filter from autozone or something stick only mobile 1 on my car

 

You should try Quaker State's Q synthetic oil, it's awsome. I always use it and K&N make a sweet oil filter.

 

Quaker State makes the WORST oil....dont use it. it is known to gum up alot. and DONT use Fram filters either they are known to break down easy and have particles leave it

 

I don't know.................Quaker State's Q forumla worked really good for my car

 

It is known for being really bad. I have never had a problem with it I used it in my first Eclipse...oh what then again that car did toss a rod threw the oil pan so im not sure, I doubt it is related though.

 

LOL bummer. Castrol isn't too bad either.

 

Well, I did some research and discovered that Mitsubishi Evo's come with Mobile 1 from the factory so I'm going to stick with Mobil 1 oil and filter. The thing that sucks is my jack doesn't fit under my EVO.....can't change the oil. I'm going to have to drive the EVO up on a couple of boards to get the jack under the car. I just ordered an APEXI turbo timer since I live in the desert and it gets pretty warm in the summer. I took the car back to the dealer a few days ago and got the gauges installed....they look sweet.

Oh, and my first victim was a 2003 Ford Mustang GT.....I didn't even really try YES!!!.[sm=icon_rock.gif]