Focus Fanatics Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
1,222 Posts
Discussion Starter · #1 ·
I know its said that the shorty header doesnt make as much power as the long tube header.
What I do like about them are the fact that the stock cat can be used with the shorty header.
Is it the difference in length that equals the power ratios?
Or is it the fact that the cat is still used on the shortys that rob power?
My plan is this:
I want to use the shorty header,but punch out the cat so its straight flow thru,than use a MIL eliminator to pass Pennsylvania state inspections.
Will this still provide gains?
I dont want to have to change everything around every time the car gets inspected.
Advice needed.
 

·
Registered
Joined
·
1,512 Posts
It will provide minimal gains. I would suggest getting an RT cat, aftermarket shorty, flexpipe, and catback for maximum gains (with the shorty).
 

·
Registered
Joined
·
8,262 Posts
A shorty header with a stock cat really doesn't do anything besides wear out the stock cat at a faster rate...if you had before and after dynos, you might notice a slight shift in the power curve (as in the engine would be making optimal output at a different range in the powerband.) You'd actually be better off getting a highflow OE-spec cat and keep the stock manifold because the stock cat is so restrictive.
 

·
FF's Night Security
Joined
·
28,766 Posts
I did that hollow out my cat but only because a shorty header demoilished before I got to the car here is a link all the info you want on power gain with the shorty it improves TQ in the lower range but gives no high end power well just check out theis link. It also has everything you need to know if you have a zetec.

http://www.sportcompactcarweb.com/projectcars/0105scc_project_ford_focus_zx3_part_1/index.html

hope that works it also lets you know how imprtant cam gears and tinning are for the zetec motor.
 

·
Registered
Joined
·
1,366 Posts
wait, why would you wanna even bother punching out the cat if you have to worry about emissions? what are the laws regarding exhausts in penn? i mean if you wanna keep a shorty setup you should just invest in a r/t highflow cat.
 

·
Registered
Joined
·
121 Posts
The cats on cars today dont restrict flow much at all. The prob with the stock cat is that the tube is 1.875", I just ordered the RT cat b/c I dont want that bottle neck there. Their cat has a 2.5" inlet and 2.250" outlet. Long tube headers alow for better tuning of the exhaust impulse running through the tubes so they dont interfear with eachother at the collector.
 

·
Registered
Joined
·
1,222 Posts
Discussion Starter · #8 ·
MIL eliminator replacng the second O2 sensor will fool the emissions test so you pass.
We have sniffer and visual tests here.
Im confused as many people are saying the cat robs great amounts of power?
Read the website link posted above...and many Thanks for posting it!
 

·
FF's Night Security
Joined
·
28,766 Posts
DueceCoupe said:
MIL eliminator replacng the second O2 sensor will fool the emissions test so you pass.
We have sniffer and visual tests here.
Im confused as many people are saying the cat robs great amounts of power?
Read the website link posted above...and many Thanks for posting it!
no prob you should read the whole project type in ford focus at there main page everthing the zetec owner needs to know.
 

·
Registered
Joined
·
1,222 Posts
Discussion Starter · #11 ·
Will do and guess I should go with the high flow cat....but can a high flow be installed anywhere in the system or in the stock location only?
If a cat can be put anywhere (ie under the car) I guess the long tube woud be the best choice after all,correct?
I just want this car to be inspectable.
 

·
Something goes here
Joined
·
8,304 Posts
If you move the cat from its stock location you will fail visual inspection. I have ahad a shorty header and high flow before, now I run a race header. IMO the shorty with high flow cat is better for normal day to day driving because you have more low and TQ, where as a race header moves your power band up into a higher rev range. Just my 2 cents
 

·
FF's Night Security
Joined
·
28,766 Posts
actully if you read the link above well all three installments of the ford focus you will see that the longtube header had all of the gains of the shorty plus it added up top past 5k rpm its does not move the powerband its just holds on to it longer. All the gains of the shorty plus more top end.
 

·
FF's Night Security
Joined
·
28,766 Posts
1 - 14 of 14 Posts
Top