I went to Midas today in my trip to get quotes for a full custom catback. I told the guy I wanted 2.25 in. piping, and he said that it'd be too big...and he's personally had experience with power loss from a 4 cylinder with 2.25 in and so has other people. Anyone ever heard of this? I thought was a conservative or just right size for a stock 4, but he said power loss is common with lower rated 4 cylinders using 2.25 piping. He recommended 2 inch...but I wanted to know if anyone here is running 2.25 in piping, and how it's holding up. I'm using an Apexi coffee can right now for my muffler, and would use the same. Thanks.

 

BS......your Mida's guy doesnt know what he's talking about..
Anyway, in most cases 2.25 inch piping should be good enough for most 4 cyl unless if you have turbo. I have the SRMotorsports Catback and very pleased w/ it. Powerwise yes its there (my SOTP dyno thinks 10hp w/ the AEM short Ram)felt mostly above 4500rpm. If your ES is 2.0, the piping should be the same as the P5s. The stock piping on the P5 is 2 inches ( i measured it before installing my Catback) and i asume its the same as the ES. Also, if youre going to custom exhaust route, make sure they "mandrell bent the pipes not crushed bent. ( thats how a performance exhaust should be). Good luck.

 

Yeah my Racing Beat cat-back is 2.375in. If I noticed gains with it, I'm sure you'll see gains at 2.25in. over the stock 2in.

 

I have an 03 MPS, and upgraded to 2 inch from the first cat back, so no second cat to cheap fart can, I have not noticed power loss. Dont know squat, but it looks and sound cool. I was told that it would increase power, didnt really feel an increase in power until I put a boost controller on the turbo.

 

ummmm 2 inch on your msp.... i think thats too small dude.... I think ure restricting airflow more than anything.... i think you should go the smallest at 2.5 inches for your msp..... and probably going upto 3 inch.....

liek man we are saying a 2 inch is too small for the naturally aspirated version of our cars..... you went 2 inch on the turbo version.... way too small man

 

2.25 is optimal for a NA 4cylinder...