Turbo back possibilty and feedback please

[Nino]

Hey guys, After speaking with GTI_James about this for ages and hearing a video of his setup I have decided I will be doing a turbo back however Im worried about the whole No cat no MOT crap and I don't want the hassle of putting a cat on every MOT.

My plan was to first get these two..... Same as James.


http://www.ebay.co.uk/itm/200627087327?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

And then...


http://www.ebay.co.uk/itm/230830744910?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

But now I want to get a sports cat, I have no idea abot these things I.E what is a 200 CPI & 100 CPI cat? 
I.E...
http://www.ebay.co.uk/itm/VW-GOLF-BORA-1-8T-20v-STAINLESS-STEEL-200-CPI-SPORTS-CAT-PIPE-EXHAUST-DOWNPIPE-/230863358957?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Model%3AGolf|Plat_Gen%3AMK+IV|Cars+Type%3A1.8+T&hash=item35c0874bed

VS

http://www.ebay.co.uk/itm/SEAT-LEON-1-8T-20v-STAINLESS-STEEL-100-CPI-SPORTS-CAT-PIPE-EXHAUST-DOWNPIPE-/230857726895?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Model%3AGolf|Plat_Gen%3AMK+IV|Cars+Type%3A1.8+T&hash=item35c0315baf

I have also noticed that the Downpipes with the cats are 2.5" where as the decat is 3" i need some expert adivse here guys 

Should I just get the 1st downpipe and then this?

http://www.ebay.co.uk/itm/2-5-EXHAUST-STAINLESS-STEEL-200-CELL-HIGH-FLOW-SPORTS-CAT-CATALYTIC-CONVETER-/330903127722?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4d0b5d06aa

But then again would it fit on the 3" downpipe? 

[rfn_hodgson]

Sorry to jack your thread but what does it mean by  200cpi and 100cpi.... Ie what's the difference??

[GTi_James]

if you are worried about it bud what i'd suggest doing is only getting the cat back for now with a reducer so that it will slip straight onto your current stock dp and cat

then in 2 months time you would of saved enough for the miltek sports cat and that way your guaranteed quality?

[beppe2672]

CPI= cells per inch, higher the number the more cells there are in the cat. So a 200 cell would give you better emissions, a 100 cell cat would be less restrictive (bigger gaps between the catalyst medium)

[Wazzzer]

CPI means cells per square inch. So the lower the number the less surface area you have for the gasses to flow past. In effect this means the more CPI you have the cleaner the emissions but it also means the gasses will be more restricted

beppe2672 damn you, I might abuse my powers and delete your response 

[beppe2672]

Lol, beat you to it!

[Nino]

Good point james, all i want to know is if i buy the 3" how would i get the sports cat to fit?

[Wazzzer]

100CPI won't pass MOT

[mar_k]

Never had an issue with not having a cat on the car, Loads of friendly MOT places.

[Rhyso]

Get yourself to ProSpeed in Cardiff

Charlie will advise and make a system to suit you. Quality of work is superb