In relative terms, no.

Yes its less restrictive, but bhp is top end power. Is it less restrictive top end? Doubt it. The downpipe and cat are strangling it. It might give more midrange torque.

Ross

i think this could go on all day to be honest, some will say yes others will say no.
i think until we have figures then all will be speculation.

having looked at the hall of fame i think all coupes will react differently to a cat back depending on the engine health.
loads of different mods giving loads of different figures and impossible to gauge what you'll get????

Yeah its all on the assumption of a healthy engine. If you take an average of cars with gtech and exhaust its 250bhp.

Ross

exactly, like i said my first coupe only had a modded airbox and gave 242bhp!! no other mods.

All that really means, is that when you add more mods, it doesnt give as much an increase. I.e adding the gtech wouldnt give you 30bhp more. It would give slightly more than stated 250 but not 30bhp ontop of the 242.

Ross

260 hp.

The end

228.4

Maybe on a significantly tuned coupe, however the standard downpipe is not going to be strangling that much an otherwise standard coupe I don't reckon.

Yeah but we are talking about 2 restrictive parts, that were designed for 220bhp, low amount of noise and to pass emissions tests.

Ross

I totally agree with that statement Ross! ho hum this could go on forever, let's leave it there

try the straw thing

well will let you all know at end of month , winner gets a 4 pack

deffo 228.4

The straw thing is an interesting analogy. TBH, it depends upon how big the restrictions are and what the flow of gas is (according so some chap called Bernoulli ) There will be pressure drop all the way down the exhaust until, pretty much at the end of the exhaust (just past it) it will be at atmosphere. Each bit of pipe (downpipe or cat say) only "sees" the pressure upstream and downstream of it. Any restrictions downstream will limit the pressure drop possible across the component: Flow = function of Pressure Drop.

What I'm trying to say (in a very long-winded way) is that the back cat bit will have some impact almost certainly but its effect will be governed by how much of a restriction it is relative to the others. Electronically minded of you can draw parallels with resistors. Voltage is the pressure drop, current is the flow of gas.

Hope that helps

Richard
Fellow of the Institution of Mechanical Engineers

237

I think I find you more interesting on the washing machine thread

Damn - I thought that might be the case PMSL