If money is tight, the T5 will do but don't put too many hard launches through it. Even the WC T5 is rated for 300-325HP flywheel. I've done a number of wheel spins and hard launches with my 347 putting out 355hp/379ft-lbs. at the wheels (well over 400hp/400 ft.lbs. flywheel) so it can handle a few, but it also depends upon how hard the donor T5 was abused. I opened mine up to check and it seemed all teeth were still sharp and only 104,000 miles. But I'm saving up for either a G-Force retrofit or just a T600 down the road and try a mid-mount shifter. That's the plan in the future when money permits.
Everyone has a budget. It's just that some are bigger than others.
IMO, always build it stronger than it needs to be. Figure out about what you need: WC T5, 3550, TKO-500, etc. Then go the next step up. You'll spend a little bit more money now for that next step up. But it saves boatloads of money and time later.
I used a TKO in mine, the strongest aftermarket trans available (before the TKO-500 and TKO-600 were available). It's bigger and heavier than a T5, and that slows you down. It feels a little notchy on the shifts, but not enough to be a problem. Cost about $300 more than the 3550. It needed a special clutch disc and output yoke. But it will never break, even with the abuse I give it.
If I was racing in competition, where every 1/2 second counts, I'd use Gordons racing trans.
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