i've just put The TBE Decat version on my Golf Gti - 3" all the way back with the 2 resonators. im removing the first one soon.
*The sound is amazing ! (Must let me bed in though before u really hear it)
*The build quality is very good.
*and you can really feel the responsiveness and power from standard.
well mine seems to have a quite abit more low torque compared to standard, as the car now flys off compared to before.
Speak with Nige at BCS he'll sort you out i reckon, the BCS modified downpipe is defiantly a must mate. + Great service and Fast delivery! Just give him a call on: 07970667189
im not sure if he has a Seat system, but if he doesn't im sure he could make one
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all in all im over the moon with mine
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Joe.