custom exaust on 172 cup, question

[a999potts]

i had a custom made exaust fitted to my mk2 172 cup last week, ive got a straight thru decat (no silencer) and 2.5 inch pipework single exit exaust also withiout silencer, does this cause a problem with lack of backpressure in engine? if so what size/kind of silencer should i get fitted to solve it and where about on the pipe work should it be fitted? also can anybody reccomend a good place in aberdeen or glasgow area to get a rolling road remap? is it better to replace ecu and remap or can you just remap standard one? any help much much appreciated!!!!!
thanks

 

[Tom]

You've fitted a pipe?

 

[a999potts]

i had one made and fitted by custo chrome in glasgow

 

[f4rt3d]

i had one made and fitted by custo chrome in glasgow

are they any good? i've got a magnex cat back stainless system on at the moment, but i want to spend some money tuning the car up...i've got a de-cat pipe, and just ordered an inlet manifold from Ben, i'll get a "proper" system made up if it's going to give improvements over a Magnex one... didn't know of any places up in Scotland that made them up though

 

[a999potts]

apparently they are excellent, my flatmate took my car into work (hes a mechanic) and all th others were very very impressed with the quality of the job and skill of the welding, sounds awesome just worried about back pressure issue!!

 

[Gaz_]

i take it you feel its lost power then?

 

[a999potts]

hard to tell, the noise makes you think youre going faster, don think ive lost power, well not enough to feel but havent gained any either! my mates keep sayin i need a silencer to increase back pressure and improve performance of engine but none of them can tell me what size or kind or where to fit it!!! any help??

 

[Gaz_]

N/A cars like our need back pressure. Alot of these custom places who make these 'straight through performance exhausts' just sling them together with no thought. Thats why alot of them perform worse than the standard system. Yes its made from kitkat wrappers but at least its designed to the engine.

 

[a999potts]

so how would you reccomend increasing back pressure? do i need a silencer? what size or kind?
thanks for help!

 

[Gaz_]

Probably need some kind of silencer etc, but kind or size....... dont know!

sorry

 

[f4rt3d]

so how would you reccomend increasing back pressure? do i need a silencer? what size or kind?
thanks for help!

have you tried a banana in the tail pipe?

 

[Gaz_]

classic lol!

 

[len_beach]

2.25'' pipework is the optimum on a standard/mildy tuned engine IIRC so any increase in back pressure would be beneficial.