I bought JBA titanium Ceramic coated LT's and mating JBA hi-flow catted H for my 2010 auto.
1 5/8" primaries, and 2.5" collector. You can also get the same LT's with a 3" collector..and also a 3" mating mid section. I used the 2.5" option, then it's all plug and play..since the oem tubing is retained from aft end of midsection..to over top the axle, then the muffler. . They come in catted or un catted H... and ditto for the X. The ceramic coating works superb. Dropped eng bay temps by 40 deg F. Part of that effect is from the ceramic coating..and part is from the hi-flow cats now residing below the front seats vs the oem cats at base of eng bay. B4 the LT install, my black steeda STB ran stupid hot to the touch, now it's barely warm.
I have a small M90 on mine, and the LT's were one of the best mods I have done to date. Take it out for a romp, with blower on 2 blocks from home, come into driveway, and within 1 min I can push down hard on any of the 8 x primaries with my fingers..and not get burnt. I believe part of the overall effectiveness of ceramic coated LT's is... the internal temps are much higher. The theory is the hotter the internal exhaust gases are, the faster they flow. The H section is a full 2.5" diam... unlike the 08-09 bullitt cars..that had a disc inside the H section, with a puny 3/8" hole dead centered in the disc.
Even without getting into boost, it pulls a lot harder than oem exhaust setup. The oem collector on the end of the oem exhaust manifold is just 2". Going from 2" to 2.5" is a 56% increase in cross sectional surface area alone..which is a bunch.
AFAIK, both Pypes + Kooks use the same 304 SS. Both are shorter than my JBA's, but pypes / kooks provide for more hp at top end. The JBA's provide more tq at the lower and mid range rpms..and still plenty at top end. It's a trade off, depending on application. You can shift the tq curve higher or lower by shortening / lengthening the overall length of the LT's. For street use, I wanted them longer.
It still pulls good and hard, right up to the rev limiter.