[wrenneth]

Hi guys,

Next month i will put on my 3 inch exhaust but i have a PLM 4-2-1 header with 2.5 inch collector.

Now i was wondering what would be best to do :

-Put in a 2.5 inch to 3 inch conversion pipe

-Or cut of the 2.5 inch collector from the plm header and weld up a 3 inch collector to the header (flex pipe) so that its true 3 inch ?

My setup is:

-EG hatch
-Stock k20a2
-CAI
-RBC
-PLM Tri-y header 4-2-1
-Going 3 inch exhaust now (currently 2.5 inch)
-Kpro

Do you think ill lose HP or TQ when changing to 3 inch collector instead of staying 2.5 inch collector because im running stock k20a2 compression and stock cams ?


The TIG welding will be done by someone who has extreme welding skills he makes motorcycle exhausts for a living ...

Thanks in advance

 

[McCoy]

2.5" collectors are the standard for Hi-Flowing headers and are backed up by dyno graphs with repeatable, proven results both by hobbyists and race teams in numerous 2.5 vs. 3.0 collector comparisons.

 

[SickSilver_ep3]

400+whp NA race motors dont even use 3 inch collectors..

 

[wrenneth]

So i qeusse best is to tapper the exhaust down to 2.5 inch to meet up with the 2.5 inch collector then for best results ?

 

[screech]

400+whp NA race motors dont even use 3 inch collectors..

rob, are there specific setups you are referring to? Just for clarification, and so it does not lead back to 'on the interwebz sicksilver said. . .'

 

[SickSilver_ep3]

rob, are there specific setups you are referring to? Just for clarification, and so it does not lead back to 'on the interwebz sicksilver said. . .'

I've seen many. They don't have 3 inch collectors. If look hard enough you can find a header pic for just about any fast all motor car. Most are side or hood exit now so it's even easier.