I have a b18b that im going to boost 6 -8 lbs at first well i have a 6lbs spring in my tial wastegate for now but i was wondering should i go 2.5 inch for my down pipe or go 3 inches? if im making like 250 whp ?

 

2.5 should be good

 

I got away with 2".



-Chris

 

Alright thanks , and you think i should buy the revhard one that some one has for sale on here for bucks shipped or should i custom make one?

 

Always go with a 3" if you can (no A/C).

 

3 inches is overkill if you are running low boost pressures like that.

 

2.5" will be good enough for 250whp.

 

2.5" will be good enough, but...........

3" downpipe = less back pressure = more horsepower and faster spool up.

There's no reason not to go with a 3", if he can.

 

Like the others said, if you can fit it, then go for it. There really shouldn't be that much of a price difference.

 

thats one of my winter project to upgrade my 2.5 DP to a 3 inch DP !! Im sure thats it a good move !

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by yellowturbo &raquo;</TD></TR><TR><TD CLASS="quote">thats one of my winter project to upgrade my 2.5 DP to a 3 inch DP !! Im sure thats it a good move ! </TD></TR></TABLE>

On your setup especially you should notice a big improvement.

 

I had an average of 30 whp gains when I swapped over to a 3" dp. My peak went up 60 hp, but torque only gained 10 ft/lb


BUT, I went from a 2.5 dp that went into a 2.25 catback. I now have a 3" dumped to the ground.