2014-2019 Fiesta ST MBRP vs Thermal R&D 3" catback comparison

I originally purchased the MBRP because my car came with a hack job exhaust and I wanted to get something better on there in a hurry. The attractive option for budget exhausts is the MBRP. Coming in at $450 before shipping, it is of an aluminized steel construction which rusts very quickly, and contains only one small resonator. The tone is extremely deep and aggressive, but it suffers from insufferable drone at almost all RPMs, especially under deceleration. This video is best enjoyed with a sound system with a subwoofer or good bass to appreciate just how low the pitch is of the MBRP. I will note that the MBRP did contain some very high quality welds and everything fit perfectly. The mounting hardware was sufficient and it also came with upgraded hangers.

The Thermal R&D Catback retails for almost double the MBRP (around $800 before shipping), but is constructed of polished stainless steel which will not rust and provides a very nice aesthetic. The difference in sound is immediately apparent. The tone is sharp and crisp, and does not contain the lowest frequencies which irritated my ears like the MBRP did. However, the most important difference is the additional (quite large) resonator that is on the rear section of this exhaust. There is no drone anywhere in the rev range and the exhaust sounds stock at idle inside the cabin with the windows up. On the outside, the ton is tame, but distinctly sportier than stock at idle. Under heavy acceleration, it provides great sound, and under deceleration there is no drone. The construction of the exhaust is very nice (to the casual observer, the welds do seem of slightly lower quality, but that is expected when comparing welds on steel vs stainless steel) and it even includes a new chassis brace that provides a very nice place for a new hanger location exclusive to this exhaust.

Overall, the MBRP does what it is meant to do, which is be cheap and loud without skimping on quality of construction. It is by no means a bad exhaust. However, the drone makes it unbearable for all but the most obnoxious of boy-racers. The Thermal R&D has less turbo whistle through the exhaust, is more quiet, and lacks all of the crackles, pops, and burbles of the MBRP, but it provides a great soundtrack and reasonable levels and with no drone. To me, it's the best Fiesta ST exhaust to buy.