Honda fits only short ( 4 into 1 pipe ), cheap & heavy cast iron * for its
engines <2.2 litre, even a F22A's *'s twin pipes are short. Result is
lower though adequate torque @ low rpm ( as during buyers' test drives )
, but very low ( <½ as much ) torque & mpg @ high ( >3000 ) rpm, this
differece rises with rpm. http://circletrack.com/techarticles/73598
My local-made 4-2-1 * [i] uses aluminised mild steel [ii] 13 kg < my
F20A's original * [iii] has longer twin pipes than a F22A's *.
In 6-02 I saw a new Civic vtec 1.6 litre engine with very short * : a waste
of vtec ( no way is torque / mpg esp @ high rpm maximised ).
Many car makers ( incl Nissan in Sunny 130Y, Hyundai in Sonata 2.4,
Proton in Waja 1.8 ) save on *, because 99.9% buyers don't test drive on
highways, or know / experienced a difference between short & long *.