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1-7/8 headers to 2” for high boost 20+

 
Old 02-16-2019, 08:13 PM
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black_c7
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Default 1-7/8 headers to 2” for high boost 20+

Hey guys

Right now im running American racing 17/8 headers, if I upgrade it to 2 in how much power and tq should I expect from that? Car will be running in the range of 20+ boost from f1x

should i consider changing to kooks instead of american racing? I found a good deal for a complete 2” headers and xpipe from kooks
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Old 02-17-2019, 11:04 PM
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robert miller
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Originally Posted by black_c7 View Post
Hey guys

Right now im running American racing 17/8 headers, if I upgrade it to 2 in how much power and tq should I expect from that? Car will be running in the range of 20+ boost from f1x

should i consider changing to kooks instead of american racing? I found a good deal for a complete 2” headers and xpipe from kooks
Your boost will drop a little going to a 2 inch from a 1 7/8 I dont like KOOKS from the way one of the guys did me there on a set of 2 inch in my c5. I like the ARH stuff better but then again I have not heard of any problems in the c7 2 inch set up in here. Robert
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Old 02-17-2019, 11:30 PM
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Originally Posted by robert miller View Post
Your boost will drop a little going to a 2 inch from a 1 7/8 I dont like KOOKS from the way one of the guys did me there on a set of 2 inch in my c5. I like the ARH stuff better but then again I have not heard of any problems in the c7 2 inch set up in here. Robert
Dropping boost = better flow (if there is no belt slip or boost leak) , but want to know how much more power to expect from that
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Old 02-18-2019, 12:34 PM
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Originally Posted by black_c7 View Post
Dropping boost = better flow (if there is no belt slip or boost leak) , but want to know how much more power to expect from that
Just from the 2 inch headers on the F1X blower at that boost level I would say around on the top end of about 20 if you got the level back up to the 20 plus level that is if your motor was over 1200 plus with the 1 7/8 headers. That was what I gain doing the same in the c5 with the F1X on the car but also I was at 427 ci motor also. I ended up at 1273 rwhp only on a BTR stage II cam. Blower, motor had more in it just needed more cam. Also running a A6 trans and was also on a mustang dyno also... Robert

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Old 02-19-2019, 09:56 PM
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Originally Posted by robert miller View Post
Just from the 2 inch headers on the F1X blower at that boost level I would say around on the top end of about 20 to 30 if you got the level back up to the 20 plus level that is if your motor was over 1200 plus with the 1 7/8 headers. That was what I gain doing the same in the c5 with the F1X on the car but also I was at 427 ci motor also. I ended up at 1273 rwhp only on a BTR stage II cam. Blower, motor had more in it just needed more cam. Also running a A6 trans and was also on a mustang dyno also... Robert
You definitely want 2” long tunes into a 3” x-pipe with your mods. Engine is a big air pump with your power level 2” will help the engine breath and as others have said make more power with lower boost.

I went with kooks due to my past history being great with them. On my Z fit and finish was perfect not one single issue. Their 3” x-pipe is nice and huge. Bolted perfectly to my Borla ATAK exhaust. I went with no cats for max power and will tell you with my F1A-94 port injection setup it’s damn race car loud. But I LOVE IT!!
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Old 02-19-2019, 11:54 PM
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Originally Posted by C5-VERT View Post
You definitely want 2” long tunes into a 3” x-pipe with your mods. Engine is a big air pump with your power level 2” will help the engine breath and as others have said make more power with lower boost.

I went with kooks due to my past history being great with them. On my Z fit and finish was perfect not one single issue. Their 3” x-pipe is nice and huge. Bolted perfectly to my Borla ATAK exhaust. I went with no cats for max power and will tell you with my F1A-94 port injection setup it’s damn race car loud. But I LOVE IT!!

from some researches i have found that arh is the same as kooks no one is better than the other, i know 2” would be better but im afraid of losing some low end power
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Old 02-20-2019, 07:24 PM
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I think Andy at DFR did a video on his channel betweeen ARH and Kooks. The bends were different if I remember. I run kooks 2 inch to their catless x pipe personally but I've heard both companies are on point with fit/finish and quality.
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Old 02-20-2019, 08:17 PM
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It’ll pickup like 10-15 hp
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Old 02-20-2019, 10:32 PM
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Originally Posted by Rdubfalco View Post
I think Andy at DFR did a video on his channel betweeen ARH and Kooks. The bends were different if I remember. I run kooks 2 inch to their catless x pipe personally but I've heard both companies are on point with fit/finish and quality.
I agree on the both but the Guys that open KOOKS headers up was working at ARH for years then went out on his on, Plus had a big heated fight over them almost being the same header almost. Robert

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Old 02-20-2019, 11:48 PM
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I considered the same “upgrade” at one point. Maybe someday I’ll do it but for me it would be to make the car even louder not for power lol
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Old 03-01-2019, 12:05 PM
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I recently switched from some crappy ebay mid-lengths to Kooks 2" + xpipe. Sadly I don't have before and after dynos, but what I will say is that the kooks were a little bit of a pain in the *** to get to seal without any leaks.

The x-pipe has about 3 joins in it (one just after collectors, one half way down, and obviously the back-box). This is good for adjustability, but you have to be mindful of putting the clamps on the right way round otherwise they foul the tunnel brace. And when they are installed the right way it is more difficult to get a wrench in there and tighten the clamps up. You need to get them REALLY tight to to prevent leaks.

I also had to try about 3 times to get the flared ends of the headers and x-pipe to mate correctly and not leak. I was swearing like trailer trash!

Last edited by jimxms; 03-01-2019 at 12:07 PM.
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