Engberg

Hey all,
I've seen several people suggest not to put a downpipe on a higher mileage motor. (mine has 65K original) They suggest using a high flow cat. Why is it recommended no to put the DP on the older motors? Any experience?

apneablue

I have read it's better to replace the DP it can clog and cause overheating issues. However, I was told by 9 out of 10 people not to replace my cat with a MP since I have a high mileage motor. But I think the DP is ok to replace but not the MP.

es

The Pre-cat & main cat are two different things. A downpipe replaces the pre-cat & that is one of the first things to you do to any FD. Midpipes on the other hand are completely different & should be replaced with HF cats unless the car is being built for all out race & power not street use.

Engberg

Ok, so this is my confussion. You can replace the pre-cat with a highflow, and that was my initial understanding of somepeople saying no DP on the high mileage cars and use a HF pre-cat. I could have my thought process backwards and am thinking of a mid-pipe..but I was pretty sure it was no replacing the pre-cat w/ DP and use a HF pre-cat. Please correct me if I'm wrong.

Engberg

Ok, I did have my thinking backwards...something made me think this was about replacing the precat. Thanks for your help guys!

QUOTE]Originally posted by apneablue

When it came time for the mid-pipe Chris tried to convince me that it wouldn't be wise since it was the original engine with 83k miles...I said I still wanted to try it if the compression numbers are good...they were all mid 8s and pretty even. so I said yes and then took off to lunch...I got a call from Chris during lunch and he said

"Are you sure you want to put a mid-pipe on this thing? Every instinct that I have says it's going to blow the engine on the dyno."
[/QUOTE]

apneablue

<------ Someone

Engberg

haha, just figured that out...you should feel uber special!