17-08-2010, 04:13 AM
Drives: Toyota Hilux surf 3.0 in blue and rust
Join Date: Aug 2006
Location: In the deep dark furthest reaches of my mind
Club ID#: 8636
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Originally Posted by darknightmare
sorry for late reply but the the idea of not going above 2.5inch for N.A is fairy tale in my experience I took off a 3.5inch put on 2.0 and the car struggled for power and resonated all the time so sounded awful too changed back to a 3.5 and boom instant power gain and sounds alot nicer too so I think it varies car to car :-)
oh and im only running a rb20e ;)
you have to look at the whole picture. my car (rb25de) has ported head and so it handles the tubular manifold and three inch pipe from cat back to the custom back box fairly well. (still needs work. )
sure you can put a 3.5 inch cat back onto a 2.0 but the whole argument is that whilst the car will rev quicker and in theory perhaps have more top end, in the lower and mid range it'll actually be flatter..less torque and will need reving inthe lower gears to make it shift.
so for easy of driving inthe lower rev range, and less need to hammer the car to get a response from it , 2.5 is the recomendation. however, much is as you say theory and dependent onthe engine. the "rules" can be bent. ...decat/cat makes a difference .. high flow/normal cat, headers or standard cast manifold...it all counts towards the individual driver character of the engine
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